Flow behaviour and microstructural evolution in cold worked 70∶30 α-brass
TL;DR: In this article, deformation behavior and microstructures at failure were investigated in a mill cold worked 70∶30 α-brass over the test temperature range of 298-973 K and strain rate range of 10−5-5×10−3 s−1.
Abstract: Deformation behaviour and microstructures at failure were investigated in a mill cold worked 70∶30 α-brass over the test temperature range of 298–973 K and strain rate range of 10−5–5×10−3 s−1. Tensile properties as a function of temperature revealed three distinct regions, with their temperature sensitivity being maximum at intermediate temperatures (553–673 K) and much less towards the lower and higher temperature ranges. Two values of activation energy for high temperature deformation Q were obtained to be 117·5 kJ mol−1 below 623 K and 196·4 kJ mol−1 above this critical temperature. In the respective temperature range the values of stress exponent n were 5·6 and 3·8. Based on the values of Q and n, the deformation mechanism was suggested to be dislocation climb creep with a probable contribution from dislocation pipe diffusion on lowering the temperature. Both grain size and cavity size were found to increase with increasing test temperature, suggesting them to be interrelated and act as an al...
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31 Jan 2014-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the microstructure, tensile deformation and fracture behavior of as-extruded CuZn5 brass alloy were investigated over a range of temperatures from 300 to 450°C and range of strain rates from 0.01 to 0.4.
Abstract: Alpha brass alloys are widely used for production of rectangular waveguides because of their low bulk resistivity. In this paper, the microstructure, tensile deformation and fracture behavior of CuZn5 brass alloy were investigated. The strain rate sensitivity and its relation to post-uniform deformation in tensile test and correlation between strain hardening exponent ( n ) and temperature were examined. The results show that strain hardening exponent decreases from 0.5 to 0.4 with increase in test temperature from 250 to 450 °C. Tensile fracture mechanisms of as-extruded CuZn5 brass alloy were studied over a range of temperatures from 300 to 450 °C and range of strain rates from 0.01 to 0.4 1/s by means of scanning electron microscope (SEM) and Atomic Force Microscope (AFM). The results show that different fracture mechanisms operate in different temperature and strain rate ranges. While transgranular dimple fracture is dominant at 300 °C and 0.4 1/s, the dominant fracture mechanism at 450 °C and 0.01 1/s is cleavage facets. Precipitations and grain boundary sliding at high temperature may be the mechanism of ductility drop. Dynamic strain ageing (DSA) did not occur since none of the manifestations of DSA are observed.
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TL;DR: In this paper, a mixture of α and β phases was obtained by milling for 100h without interruptions and the three elements simultaneously gave the best ratio between the amount of β phase and the milling time.
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01 Jan 2012
139,059 citations
"Flow behaviour and microstructural ..." refers background in this paper
...Such cavity evolution was also reported by Greenwood et al.5 It is worth noting that the ductility is also reduced at 773 and 873 K owing to 4 Arrhenius plot at different strain rates intergranular cracking developed at these temperatures....
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...Such cavity evolution was also reported by Greenwood et al.(5) It is worth noting that the ductility is also reduced at 773 and 873 K owing to 4 Arrhenius plot at different strain rates...
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Book•
01 Jan 1985
TL;DR: In this paper, the International System of Units (SI) is used to measure the properties of materials and their properties in the context of materials science and engineering, including properties of metal alloys.
Abstract: List of Symbols.Introduction.Atomic Structure and Interatomic Bonding.The Structure of Crystalline Solids.Imperfections in Solids.Diffusion.Mechanical Properties of Metals.Dislocations and Strengthening Mechanisms.Failure.Phase Diagrams.Phase Transformations in Metals: Development of Microstructure and Alteration of Mechanical Properties.Thermal Processing of Metal Alloys.Metals Alloys.Structures and Properties of Ceramics.Applications and Processing of Ceramics.Polymer Structures.Characteristics, Applications, and Processing of Polymers.Composites.Corrosion and Degradation of Materials.Electrical Properties.Thermal Properties.Magnetic Properties.Optical Properties.Materials Selection and Design Considerations.Economic, Environmental, and Societal Issues in Materials Science and Engineering.Appendix A: The International System of Units (SI).Appendix B: Properties of Selected Engineering Materials.Appendix C: Costs and Relative Costs for Selected Engineering Materials.Appendix D: Mer Structures for Common Polymers.Appendix E: Glass Transition and Melting Temperatues for Common Polymeric Materials.Glossary.Answers to Selected Problems.Index.
6,674 citations
TL;DR: In this article, it is suggested that mosaic boundaries and boundaries between grains of nearly the same orientation may not serve as sources or sinks of the diffusion currents, in which case the creep rate will depend only on the configuration of grain boundaries having a sizable orientation differen...
Abstract: According to a suggestion of Nabarro, any crystal can change its shape by self‐diffusion in such way as to yield to an applied shearing stress, and this can cause the macroscopic behavior of a polycrystalline solid to be like that of a viscous fluid. It is possible that this phenomenon is the predominant cause of creep at very high temperatures and very low stresses, though not under more usual conditions. The theory underlying it is developed quantitatively, and calculations of rate of creep, or equivalently of effective viscosity, are given for aggregates of quasi‐spherical grains and for wires composed of cylindrical grains. Allowance is made for the effect of tangential stress relaxation at the grain boundaries. It is suggested that mosaic boundaries and boundaries between grains of nearly the same orientation may be unable to serve as sources or sinks of the diffusion currents, in which case the creep rate will depend only on the configuration of grain boundaries having a sizable orientation differen...
2,214 citations
TL;DR: Bulk metal working processes are carried out at elevated temperatures where the occurrence of simultaneous softening processes would enable the imposition of large strains in a single step or multi-step process.
Abstract: Bulk metal working processes are carried out at elevated temperatures where the occurrence of simultaneous softening processes would enable the imposition of large strains in a single step or multi...
622 citations
02 Jun 1995
616 citations
"Flow behaviour and microstructural ..." refers background or result in this paper
...The values of activation energy for intrinsic diffusion of Cu and Zn in 70 : 30 a-brass were found to be 175 and 165 kJ mol(21) respectively.(38) As the activation energy value for deformation obtained in the present study at higher temperature is 196?4 kJ mol(21) and nc is equal to 3?8, the mechanism for deformation is identified to be dislocation climb creep....
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...The values of stress exponents for creep according to dislocation viscous glide controlled and dislocation climb controlled mechanisms are 3 and 4?5 respectively.(38) Comparison of these values with that obtained in the present work suggests that both dislocation viscous glide and dislocation climb mechanisms operate depending on test temperature....
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