Stress-strain rate relations for high-temperature deformation of two-phase Al-Cu alloys
01 Oct 1995-Journal of Materials Science (Kluwer Academic Publishers-Plenum Publishers)-Vol. 30, Iss: 20, pp 5065-5072
TL;DR: In this article, the mean free path between θ particles was suggested to be a more appropriate microstructural parameter for the constitutive relationship for deformation of the Al-Cu alloys.
Abstract: Al-Cu alloys containing 6, 11, 17, 24 and 33 wt% Cu, annealed for 0.5–100 h, were deformed by the differential strain-rate test technique over a strain-rate range of ≈4×10−6 to 3×10−2s−1 at temperatures ranging from 460–540°C. Superplastic behaviour, with strain-rate sensitivity, m≈0.5, and activation energy, Q=171.5 kJ mol−1, is shown by the Al-24Cu and Al-33Cu alloys at lower strain rates and higher temperatures. All the alloys show m≲0.20 at higher strain rates, but the average activation energy for deformation of the Al-6Cu, Al-11Cu, and Al-17Cu alloys is evaluated to be 480.7 kJ mol−1, in contrast to a lower value of 211 kJ mol−1 for the Al-24Cu and Al-33Cu alloys. Instead of grain size, the mean free path between θ particles is suggested to be a more appropriate microstructural parameter for the constitutive relationship for deformation of the Al-Cu alloys.
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TL;DR: In this article, a ternary eutectic system was proposed for multiphase Ni-25Al-25Cr alloy, which has superplasticity under appropriate conditions.
15 citations
TL;DR: In this paper, the processing of Al-Cu alloys via a novel powder-metallurgy route is discussed, where the specific technique used for powder processing involves the rapid solidification of coarse, molten droplets following impulse atomization.
Abstract: This paper concerns the processing of Al-Cu alloys via a novel powder-metallurgy route. The specific technique used for powder processing involves the rapid solidification of coarse, molten droplets following impulse atomization. This produces a fine, homogeneous, dendritic microstructure within the alloy granules. Following consolidation via hot pressing, the microstructure consists mostly of an Al matrix with fine CuAl2 particles and partially recrystallized dendrites. Further heat treatment and/or thermomechanical processing completes the spheroidization process in the CuAl2 phase. Blending powders with different Cu has been used to make materials with a bimodal distribution of the local particle-volume-fraction content. The high temperature (773 K) strength of these materials decreases with increasing CuAl2 content. This can be explained using a flow model based on superplastic deformation, controlled by diffusion-accommodated sliding at Al grain boundaries. This mechanism may also explain the deformation-enhanced particle coarsening observed during channel-die forging operations.
13 citations
TL;DR: In this article, a grain boundary sliding-based mechanism is proposed as being responsible for the observed superplasticity of a multiphase NiAl-based intermetallic alloy and it is observed that cavities are usually aligned parallel to the extrusion direction and the tensile axis.
7 citations
TL;DR: In this article, a Gleeble® thermo-mechanical simulator combined with microstructure characterization using a field emission scanning electron microscope was used to provide insights into seam weld formation during resistance welding (RW).
Abstract: A Gleeble® thermo-mechanical simulator combined with microstructure characterization using a field emission scanning electron microscope was used to provide insights into the seam weld formation during resistance welding (RW). Gleeble® was used to physically/microstructurally simulate the seam weld formation during RW for the first time. It was found that a peak temperature of 1500 ̊C and 10-mm stroke produced a microstructure in the solid-state bondline, the flash, and the heat-affected zone similar to the resistance welded pipe manufactured in an industrial scale. Using the force response obtained during seam weld formation in Gleeble®, microstructure characterization of the seam weld, and thermodynamic calculations, it is proposed the seam weld in a resistance weld consists of a mushy zone with delta ferrite and solute-enriched liquid, which solidifies into austenite, and on post welding cooling, transforms into ferrite and stringers of M/A, respectively. The presence of a mushy zone in the weld joints provides a physical explanation for the “decarburization” phenomenon observed in the seam of resistance welds.
6 citations
TL;DR: In this paper, the deformation resistance of spray formed binary alloys AlCu10, AlCul7 and AlCu24 has been investigated in view of their density, microstructure and forming performance.
Abstract: Spray formed binary alloys AlCu10, AlCul7 and AlCu24 have been investigated in view of their density, microstructure and forming performance. The forming properties have been determined by means of plasto-dilatometry. With higher copper contents the resistance against deformation increases, but sufficient deformation at elevated temperatures is still possible. Microstructural investigations explain the dependence of the deformation resistance upon the degree of dispersion of the Al 2 Cu-phase.
2 citations
References
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01 Sep 1951
TL;DR: In this paper, an attempt is made to explain the observed phenomena in the yielding and ageing of mild steel, described in two previous papers, in the general terms of a grain-boundary theory.
Abstract: An attempt is made here to explain the observed phenomena in the yielding and ageing of mild steel, described in two previous papers, in the general terms of a grain-boundary theory. On this hypothesis, a satisfactory explanation of the variation of the lower yield point with grain size may be developed. It is shown that strain-ageing must involve two processes: a healing of the grain-boundary films, coupled with a hardening in the grains themselves. A discussion of the possible nature of the grain-boundary film is also undertaken.
5,893 citations
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01 Jan 1949
TL;DR: In this paper, the authors present an X-ray analysis of metallic materials and their properties, such as elastic properties, damping capacity and shape memory alloys, as well as their properties of metal and alloys.
Abstract: General physical and chemical constants X-ray analysis of metallic material Crystallography Crystal chemistry Metallurgically important minerals Thermochemical data Physical properties of molton salts Metallography Equilibrium diagrams Gas-metal systems Diffusion in metals General physical properties Elastic properties, damping capacity and shape memory alloys Temperature measurement and thermoelectric properties Radiating properties of metals Electron emission Electrical properties Magnetic materials and their properties Mechanical testing Mechanical properties of metals and alloys Sintered materials Lubricants Friction and wear Casting alloys and foundry data Engineering ceramics and refractory materials Fuels Heat treatment Metal cutting and forming Corrosion Electroplating and metal finishing Welding Soldering and brazing Vapour deposited coatings and thermal spraying Superplasticity Metal-matrix composites Non-conventional and emerging metallic minerals modelling and simulation supporting technologies for the processing of metals and alloys.
3,593 citations
"Stress-strain rate relations for hi..." refers result in this paper
...As the former value of Q is in agreement with the activation energy of the 0 phase, as well as for lattice diffusion in pure copper (211 kJ tool-1) [ 35 ], the deformation in Region III is suggested to occur by a dislocation climb mechanism [36]....
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622 citations