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Failure analysis of a martensitic stainless steel (CA-15M) roll manufactured by centrifugal casting. Part I: Material and fractographic characterization

Azevedo, Cesar Roberto de Farias; Maia, Rafael Rocha; Echeverri, Edwan Anderson Ariza; Tschiptschin, Andre Paulo
Fonte: Oxford Publicador: Oxford
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
45.85%
The failure analysis of a martensitic stainless steel (CA-15M) roll manufactured by centrifugal casting and used in cast glass rolling was carried out by means of traditional characterization techniques (optical metallography, SEM, EDX microanalysis, tensile testing and XRD). The roll was in the as-cast condition and its microstructure featured large proportion of δ ferrite (between 20% and 27%) in a martensitic (α′) matrix, with the δ/α′ interfaces presenting an intergranular network of M23C6 carbides. The crack propagation began in the internal surface of the roll, with δ/α′ intergranular and transgranular cleavage in the “equiaxed region” of the casting, progressing to δ/α′ intergranular ductile fracture in the “columnar” and “chilled regions”. Tensile thermal stresses in the internal surface of the roll associated with microstructural embrittlement (network of interfacial carbide and microporosities) are thought to be the main causes for the premature failure of the roll. Finally, materials selection was performed to replace the CA-15M stainless steel with another class of stainless steel for centrifugal casting

Subsídios para seleção de materiais poliméricos termoplásticos.; Termoplastic material selection aids.

Sant'Anna, José Alex Piccolo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/08/2007 PT
Relevância na Pesquisa
36.07%
A constante evolução dos Materiais Poliméricos e seus compostos, a procura por um melhor desempenho e redução de peso em peças técnicas, têm levado a busca de soluções inovadoras em materiais termoplásticos para peças tradicionalmente produzidas em materiais metálicos. Nestes casos, a fase inicial de um projeto deve ser realizada com muito cuidado e é onde as metodologias de Seleção de Materiais e Processos de Fabricação (SMPF) mais podem contribuir para o sucesso de um produto. Existem muitas ferramentas para seleção de materiais, algumas delas até mesmo voltadas especificamente aos polímeros, mas nota-se que uma metodologia adequada - e talvez específica - ainda seja necessária. O objetivo deste trabalho foi analisar os métodos utilizados na academia e na indústria para a seleção de materiais termoplásticos, bem como os bancos de dados e programas de computador disponíveis, na busca de subsídios para auxiliar profissionais de projeto de produtos, sejam eles engenheiros ou não. Assim, tratou-se inicialmente de aspectos de Engenharia de Materiais e de SMPF e especificamente de Materiais Poliméricos termoplásticos, na busca de oferecer uma base comum por meio de definições e premissas utilizadas. Como é de interesse entender a inserção da filosofia de SMPF na indústria de transformação de materiais termoplásticos...

Metodologia enxuta para desenvolvimento de componentes estruturais, suportada por ferramentas de projeto, processo de manufatura e ensaios de materiais; Lean development methodology for structural components development supported by design tools, manufacturing process and materials testing

Spinelli, Daniel Müller
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 05/10/2012 PT
Relevância na Pesquisa
45.79%
Diversas propostas para o desenvolvimento de novos produtos vêm sendo elaboradas com o objetivo de acelerar a homologação final e permitir o lançamento com a confiabilidade necessária para minimizar danos à sociedade e à empresa. Este trabalho explora de forma objetiva o contexto de projeto para um componente estrutural de suspensão, de elevado nível de segurança, propondo uma metodologia para sistematização de planejamento enxuto das fases, considerando as atividades técnicas que geram valor ao processo, aplicando as ferramentas disponíveis de engenharia desde a definição de uma arquitetura ótima, e a partir desta, realizar o detalhamento nas fases de projeto, protótipo e testes finais. O objetivo principal foi liberar a confecção de um ferramental definitivo de forma antecipada ao desenvolvimento tradicional, e, portanto foram avaliados os resultados fundamentais que podem ser entregues, por meio de modelagem, simulação e ensaios experimentais, de cunho tecnológico, manufatura e econômico, para servirem de informações em uma tomada de decisão que envolve grande quantia monetária. Adicionalmente, uma proposta de homologação da integridade estrutural para um novo produto foi explorada por meio da seleção de materiais...

Seleção de materiais para embalado de transporte de Mo-99; Material selection for a transportation package of Mo-99

Hara, Débora Harumi Suzuki
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 05/03/2015 PT
Relevância na Pesquisa
46.09%
O transporte de materiais radioativos deve ser realizado em embalados capazes de suportar tanto condições normais, quanto acidentais de transporte. O objetivo deste trabalho foi a seleção de materiais que possam viabilizar a fabricação de um embalado para o transporte de substâncias que sejam fontes de alta radioatividade, em especial o Mo-99, cujo produto do decaimento radioativo é o Tc-99m, utilizado para fins diagnósticos na medicina nuclear. Para tanto, foi realizada a seleção dos possíveis materiais que podem ser utilizados para a fabricação de um embalado, com o auxílio do programa CES EduPack e a metodologia desenvolvida por Ashby. O programa ESTAR foi utilizado para verificar a ocorrência de radiação de freamento e o programa XCOM para o cálculo do coeficiente de atenuação da radiação gama de alguns dos materiais selecionados para compor a blindagem do embalado. Posteriormente, a espessura necessária para a blindagem da radiação foi calculada. A partir dos resultados obtidos, os materiais selecionados como candidatos potenciais para a fabricação da blindagem foram as ligas de tungstênio. Com relação à parte do embalado que oferece isolamento térmico e proteção ao impacto, destacam-se as madeiras...

Determination of material/geometry of the section most adequate for a static loaded beam subjected to a combination of bending and torsion

Silva, Hugo Miguel; Meireles, José F.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Artigo de Revista Científica
Publicado em //2013 ENG
Relevância na Pesquisa
46.04%
The acceleration of industrial machines mobile parts has been increasing over the last few years, due to the need of higher production in a short period of time. The machines were dimensioned for a lower value of acceleration, which means there is not enough rigidity for the correct operation at much higher accelerations. Nowadays, the accelerations can be near 12 times the acceleration of gravity. There is the need of improving rigidity to make possible the correct machine operation without undesired vibrations that can ultimately lead to failure. The main applications of this work are plotters and laser cutting machines. To improve rigidity, one must improve the relevant material properties, and the relevant geometric variables of the model.[1] A novel Finite Element Model Updating methodology is presented in this paper. The considered models were : a ribbed plate and a tubular beam. The models were built by means of the Finite Element Method (FEM), and MATLAB was used to control the optimization process, using a programming code. Both material properties and geometric parameters were optimized. The main aim of the materials modeling is to know how the value of the objective function changes with the value of the material properties. Materials selection was performed...

Materials selection as an interdisciplinary technical activity: basic methodology and case studies

Ferrante,M.; Santos,S.F.; Castro,J.F.R. de
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2000 EN
Relevância na Pesquisa
66.11%
The technical activity known as Materials Selection is reviewed in its concepts and methodologies. Objectives and strategies are briefly presented and two important features are introduced and discussed; (i) Merit Indices: a combination of materials properties, which maximises the objectives chosen by the designer and (ii) Materials Properties Maps: a bi-dimensional space whose coordinates are pairs of properties in which materials can be plotted and compared directly in terms of their merit indices. A general strategy for the deduction of these indices is explained and a formal methodology to establish a ranking of candidate materials when multiple constraints intervene is presented. Finally, two case studies are discussed in depth, one related to materials substitution in the context of mechanical design and a less conventional case linking material selection to physical comfort in the home furniture industry.

Selection methodologies of materials and manufacturing processes

Santos,Sydney Ferreira; Ferrante,Maurizio
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2003 EN
Relevância na Pesquisa
56.15%
The present work discusses some principles of materials selection and examines a few selection criteria and contexts in which this technical activity takes place. Emphasis is given to the concept of Merit Indices, and to the methodology employed for its deduction. The Materials Properties Charts and their integration with the Merit Indices are introduced and illustrated by the former of the two case studies here presented whilst the second associates the methodology of materials selection to process selection.

A Combined Finite Element-Multiple Criteria Optimization Approach for Materials Selection of Gas Turbine Components

Shanian, A.; Milani, Abbas S.; Vermaak, Natasha; Bertoldi, Katia; Scarinci, Tom; Gerendas, Miklos
Fonte: ASME International Publicador: ASME International
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
56.05%
The design of critical components for aerospace applications involves a number of conflicting functional requirements: reducing fuel consumption, cost, and weight, while enhancing performance, operability and robustness. As several materials systems and concepts remain competitive, a new approach that couples finite element analysis (FEA) and established multicriteria optimization protocols is developed in this paper. To demonstrate the approach, a prototypical materials selection problem for gas turbine combustor liners is chosen. A set of high temperature materials systems consisting of superalloys and thermal barrier coatings is considered as candidates. A thermo-mechanical FEA model of the combustor liner is used to numerically predict the response of each material system candidate. The performance of each case is then characterized by considering the material cost, manufacturability, oxidation resistance, damping behavior, thermomechanical properties, and the FEA postprocessed parameters relating to fatigue and creep. Using the obtained performance values as design criteria, an ELECTRE multiple attribute decision-making (MADM) model is employed to rank and classify the alternatives. The optimization model is enhanced by incorporating the relative importance (weighting factors) of the selection criteria...

D,L-Cyclic Peptides as Structural Materials

Rubin, Daniel James
Fonte: Harvard University Publicador: Harvard University
Tipo: Thesis or Dissertation; text Formato: application/pdf
EN
Relevância na Pesquisa
45.88%
The bioengineer has a choice of building with proteins, peptides, polymers, nucleic acids, lipids, metals and minerals, each class containing tremendous diversity within its category. While the platforms are diverse, they can be unified by a common goal: to engineer nano- and micro-scale order to improve functionality. In doing so, self-assembling systems aim to bring the lessons learned from the order in natural systems83 into the therapeutics, materials, and electronics that society uses every day. The rigid geometry and tunable chemistry of D,L-cyclic peptides make them an intriguing building-block for the rational design of nano- and microscale hierarchically structured materials. Herein, we utilize a combination of electron microscopy, nanomechanical characterization including depth sensing-based bending experiments, and molecular modeling methods to obtain the structural and mechanical characteristics of cyclo-[(Gln-D-Leu)4] (QL4) assemblies. QL4 monomers assemble to form large, rod-like structures with diameters up to 2 μm and lengths of 10s to 100s of μm. Image analysis suggests that large assemblies are hierarchically organized from individual tubes that undergo bundling to form larger structures. With an elastic modulus of 11.3 ± 3.3 GPa...

Application of multi-attribute utility analysis to problems in materials selection

Field, Frank Remsen
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 231 leaves; 10336763 bytes; 10336517 bytes; application/pdf; application/pdf
ENG
Relevância na Pesquisa
45.79%
by Frank Remsen Field III.; Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Material Science and Engineering, 1985.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.; Vita.; Bibliography: leaves 208-229.

Alloy design or three-dimensional printing of hardenable tool materials

Guo, Honglin, 1965-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 174 leaves; 8524668 bytes; 8524474 bytes; application/pdf; application/pdf
ENG
Relevância na Pesquisa
55.88%
Three-dimensional printing (3DP) is a state-of-the-art manufacturing technology, One of its many important applications is to fabricate the metal tooling for plastic injection molding. In order to achieve a fully dense 3DP metal tool, the current 3DP process involves five steps: printing, debinding, sintering, liquid metal infiltration and heat treatment. Due to the infiltration requirement, all 3DP tools made to date are composed of a high-strength skeleton material and a low-strength infiltrant. The search for a hardenable/hard 3DP system is the mission of this dissertation. Five major accomplishments can be found in the dissertation: (1) development of the 420/bronze material system for 3DP tooling; (2) development and optimization of the post-processing of the system; (3) development of a computer model simulating the interaction of powder/liquid infiltrant; (4) computer-aided material system design and (5) methodology exploration of the material system development.The 420/bronze material system with a minimum reaction was developed experimentally, by screening 30 potential material systems. Compared to the initial 3DP and reactive system, the system strength was significantly improved. More than 50 3DP injection tools have been fabricated using this material system. A 3DP tool made of the 420/bronze system has been used to mold more than one hundred thousand plastic products without major repairing of the tool. It was the first time that an injection mold was made of 60 vol% 420 and 40 vol% bronze. The system was a milestone in the 3DP material system development. In addition...

Molecular insights on the solvent effect of methanol additive in glycine polymorph selection

Patala, Srikanth
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 85 p.
ENG
Relevância na Pesquisa
45.97%
In an effort to improve control and design in organic crystallization, the effect of solvent on polymorph selection has gained tremendous interest in recent years. In this thesis, molecular simulation techniques are used to gain insight into the solvent effect on glycine crystallization in water-methanol mixtures. We report the validation of the Optimized Potential for Liquid Simulations (OPLS) force field and parameters with modified Lennard-Jones parameters for hydrogens attached to a-carbon in glycine zwitterion. Solution and interface simulations in water and 50% v/v water-methanol solutions reveal the mechanism through which methanol additive results in the crystallization of the least stable [Beta]-glycine polymorph. Free energy calculations through the Umbrella Sampling method show an increased stability of the centrosymmetric dimer structure ([alpha]-glycine growth unit) in the presence of the methanol additive. Even though the dimer structure is more stable in water-methanol mixtures, a higher fraction of glycine monomers were observed in water-methanol mixtures. It is revealed through thermodynamic arguments that a drastic decrease in solubility results in a higher fraction of glycine monomers in water-methanol mixtures. It was hypothesized in previous studies that the presence of monomer units docking onto the (010) interface of [alpha]-glycine inhibits further growth due to exposed ammonium groups at the interface. The effect of solvent on crystal growth inhibition is explored by the interface simulations of a-glycine in water-methanol mixtures. When the monomer units are docked onto the interface...

Light-weight materials selection for High-Speed Naval Craft

Torrez, Joseph B.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Tese de Doutorado Formato: 111 p. : ill.
Relevância na Pesquisa
56.16%
CIVINS; A decision analysis study was conducted on the process of materials selection for high-speed naval craft using the Modified Digital Logic (MDL) method. The purpose is to show how this method along with Ashby's material selection process can be integrated to provide a comprehensive tool designed specifically for light-weight material optimization. Using Ashby's Material Selection Charts and the MDL method, a step by step material selection process is outlined. Furthermore, a comparison of the materials based on equivalent plate uni-axial ideal elastic compressive stress was completed using the American Bureau of Shipbuilding (ABS) Guide for Building and Classing High-Speed Naval Craft and then an evaluation was done to optimize material selection depending on the designer's preference for weight and cost, The potential materials for evaluation were selected using Naval Sea Systems Command (NAVSEA) references for the most current materials in use, or being evaluated, for light weight naval construction. The results demonstrate the feasibility of using the MDL method to select one or more materials based on desired mechanical and structural characteristics. The study also introduces the potential use of non-traditional materials in Naval Architecture...

Architecture and materials selection in multi-materials design

BARACCHINI, Paul; GUILLEBAUD, Claire; KROMM, François-Xavier; CATAPANO, Anita; MONTEMURRO, Marco; WARGNIER, Hervé
Fonte: Arts et Métiers ParisTech Publicador: Arts et Métiers ParisTech
EN
Relevância na Pesquisa
56.07%
The design process involving both the architecture and the materials represents an hard task mainly due to the high number of potential configurations, thus requiring firstly the development of new and more rigorous approaches but also the development of new tools. To this purpose, we present in this work a new strategy for the design of architectured materials. Such a strategy relies on one hand on the construction of some databases for the selection of both geometrical patterns and materials, and on the other hand on the use of well-known analytical models to describe the physical behaviour of the multi-material. In order to prove its effectiveness, we apply our strategy to the problem of the least-weight design of a multilayer plate that has to meet thermal, electrical and mechanical requirements. Moreover, we use a genetic algorithm, as a numerical tool, to perform the solution search for our problem. Numerical results show that we can obtain optimum configurations characterised by a weight saving up to 59% keeping the same (or even superior) thermal, electrical and stiffness properties than those of a monolithic reference plate.

Engenharia e design : contribuição ao estudo da seleção de materiais no projeto de produto com foco nas características intangíveis; Engineering and design: contribution to the study of materials selection in product design with focus on the intangible characteristics

Faller, Roberto da Rosa
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
46.04%
Nos anos recentes, evidenciou-se o destaque de outros aspectos dos produtos além dos ligados ao bom funcionamento e usabilidade. Estudos nesse âmbito trouxeram à tona a importância da relação emocional envolvida na interação indivíduo-objeto. Intermediando essa relação estão os materiais, elementos capazes de transferir parte de sua personalidade aos produtos por meio de suas características tangíveis e intangíveis. O estudo dos aspectos técnicos dos materiais é amplamente apoiado por diferentes programas computacionais, livros e pesquisas científicas. Já seus aspectos ligados à subjetividade não encontram suporte semelhante. Assim, os métodos de Seleção de Materiais e as fontes de pesquisa existentes mostram-se incapazes de dar o suporte exigido pelo projeto de produtos com foco no usuário. Dessa forma, o presente trabalho apresenta contribuições ao processo de Seleção de Materiais em Design de Produto, destinadas a capacitar os projetos na incorporação de aspectos emocionais. É proposto, então, um modelo de elucidação das emoções, que demonstra e relaciona as variáveis envolvidas durante a interação indivíduo-objeto; são apresentadas duas pesquisas de campo que visam levantar atributos verbais utilizados na descrição de produtos e materiais e é proposto...

Electrothermal controlled-exposure technology

Maloney, John Mapes
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 79 p.
ENG
Relevância na Pesquisa
45.82%
A technology is presented for exposing the contents of microfabricated cavities in a substrate. These contents are hermetically sealed until exposure is triggered by an electronic signal. The exposure mechanism uses electrothermal heating to rupture a metal membrane at one end of the cavity. The device's capability for storing a variety of contents and exposing them on demand makes it well suited for periodic exposure of new sensors as old ones degrade. Two commercialization possibilities are investigated: biowarfare agent detection and in vivo glucose sensing. Both applications employ sensing mechanisms that can be miniaturized and packaged in an array. These sensors are susceptible to fouling or degradation over time from environmental factors. The controlled-exposure technology addresses this problem by periodically exposing fresh sensors. The two applications are thought to be especially favorable markets because of the need for reliable, continuous sensing. The engineering aspects of the technology are investigated by identifying key material properties for each component of the device.; (cont.) The key properties for the substrate material are suggested to be its vapor permeability and suitability for cavity formation. The most important properties of the membrane are its electrical requirements (the current and voltage required to expose or "activate" the device)...

Multilayer composite photonic bandgap fibers; Composite photonic bandgap fiber materials and fabrication

Hart, Shandon D. (Shandon Dee), 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 126 leaves; 6020400 bytes; 6018127 bytes; application/pdf; application/pdf
ENG
Relevância na Pesquisa
56.09%
Materials and fabrication techniques are developed that lead to the successful fabrication of multilayer composite photonic bandgap fibers. The pertinent background in electromagnetic theory of multilayer dielectric mirrors and optical fibers is surveyed. Materials properties constraints are outlined, with emphasis on those constraints related to processing strategy and ultimate target length scale. Interfacial energy is measured in a chalcogenide glass / organic polymer composite system selected for fiber fabrication. A classical capillary instability model is employed to predict the feasibility of fiber fabrication based on material properties; from this model, quantitative materials selection criteria related to ultimate length scale are derived. Good agreement is found between the calculated materials selection criteria and controlled fiber experiments. The fiber fabrication techniques are described and analyzed; chalcogenide film deposition is characterized using Raman and electron microprobe spectroscopy, and heat transfer during fiber drawing is modeled using a commercial finite-element software package. The developed materials and fabrication processes are used to perform two case studies in novel photonic bandgap fiber fabrication; the first case study deals with externally reflecting omnidirectional 'mirror-fibers'...

Light-weight materials selection for high-speed naval craft

Torrez, Joseph B. (Joseph Benjamin)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 111 p.
ENG
Relevância na Pesquisa
46.15%
A decision analysis study was conducted on the process of materials selection for high-speed naval craft using the Modified Digital Logic (MDL) method proposed by B. Dehgham-Manshadi et al in ref [17]. The purpose is to show how this method along with Ashby's material selection process can be integrated to provide a comprehensive tool designed specifically for light-weight material optimization. Using Ashby's Material Selection Charts and the MDL method, a step by step material selection process is outlined. Furthermore, a comparison of the materials based on equivalent plate uni-axial ideal elastic compressive stress was completed using the American Bureau of Shipbuilding (ABS) Guide for Building and Classing High-Speed Naval Craft and then an evaluation was done to optimize material selection depending on the designer's preference for weight and cost. The potential materials for evaluation were selected using Naval Sea Systems Command (NAVSEA) references for the most current materials in use, or being evaluated, for light weight naval construction. The results demonstrate the feasibility of using the MDL method to select one or more materials based on desired mechanical and structural characteristics. The study also introduces the potential use of non-traditional materials in Naval Architecture...

Similarity Measuring Approuch for Engineering Materials Selection

Doreswamy; Vanajakshi, M. N.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 02/01/2013
Relevância na Pesquisa
46.03%
Advanced engineering materials design involves the exploration of massive multidimensional feature spaces, the correlation of materials properties and the processing parameters derived from disparate sources. The search for alternative materials or processing property strategies, whether through analytical, experimental or simulation approaches, has been a slow and arduous task, punctuated by infrequent and often expected discoveries. A few systematic efforts have been made to analyze the trends in data as a basis for classifications and predictions. This is particularly due to the lack of large amounts of organized data and more importantly the challenging of shifting through them in a timely and efficient manner. The application of recent advances in Data Mining on materials informatics is the state of art of computational and experimental approaches for materials discovery. In this paper similarity based engineering materials selection model is proposed and implemented to select engineering materials based on the composite materials constraints. The result reviewed from this model is sustainable for effective decision making in advanced engineering materials design applications.; Comment: International Journal of Computational Intelligence Systems (IJCIS)...

Materials Selection for Oxide-based Resistive Random Access Memories

Guo, Yuzheng; Robertson, John
Fonte: AIP Publishing Publicador: AIP Publishing
Tipo: Article; accepted version
EN
Relevância na Pesquisa
45.85%
This is the accepted manuscript. The final published version is available from AIP at http://scitation.aip.org/content/aip/journal/apl/105/22/10.1063/1.4903470.; The energies of atomic processes in resistive random access memories (RRAMs) are calculated for four typical oxides, HfO2, TiO2, Ta 2O5, and Al2O3, to define a materials selection process. O vacancies have the lowest defect formation energy in the O-poor limit and dominate the processes. A band diagram defines the operating Fermi energy and O chemical potential range. It is shown how the scavenger metal can be used to vary the O vacancy formation energy, via controlling the O chemical potential, and the mean Fermi energy. The high endurance of Ta 2O5 RRAM is related to its more stable amorphous phase and the adaptive lattice rearrangements of its O vacancy.; The authors thank EPSRC for funding by the project ?Alien?.