Authors: Masahiko Ikeda, S. Komatsu, Yuichiro Nakamura, Y. Kobayashi
Abstract: Using Ti-40mass%Ta-0, -4, -8 and -12mass%Sn alloys, the effect of Sn addition on phase
constitution in the solution treated and quenched state and isochronal heat treatment behavior is
studied by electrical resistivity and Vickers hardness measurements and X-ray diffactometry. To
confirm shape memory effect of some of these alloys, shape-recovery test was also performed.
Orthorhombic martensite, was identified in Ti-40Sn-0 to 8Sn alloy quenched from 1173K, while
phase was identified in STQed Ti-40Ta-12Sn alloy. On isochronal heat treatment, increases of
resistivity at LN and resistivity ratio were observed in only 8Sn alloy, because these increases are
due to reverse-transformation of to phase. From result of shape recovery test, shape memory
effect was observed in Ti-40Ta-4 and 8Sn alloys
1273
Authors: Chihiro Watanabe, Fumiya Nishijima, Ryoichi Monzen, Kazue Tazaki
Abstract: The effects of P and Cr addition and two-step aging on the microstructure and mechanical
properties of a Cu-4wt%Ni-0.95wt%Si alloy have been examined. The addition of 0.02wt%P
improves both strength and elongation because it suppresses discontinuous precipitation reaction. The
Cr addition to the Cu-Ni-Si-P alloy decreases greatly the grain size, resulting in an increase in
elongation. Two-step aging, pre-aging at 300 or 350oC and subsequent second-step aging at 450oC,
causes an increase in strength without reducing elongation. The increase in strength is attributable to
the decrease in inter-precipitate spacing by the two-step aging. The two-step aged Cu-4wt%Ni-
0.95wt%Si-0.02wt%P-0.02wt%Cr alloy attains a tensile strength of 830MPa, an elongation of 13%
and an electrical conductivity of 35%IACS.
2321
Authors: M. Kolář, Vladivoj Očenášek, J. Uhlíř, Ivana Stulíková, Bohumil Smola, Martin Vlach, V. Neubert, K. Šperlink
Abstract: The influence of plastic deformation and heat-treatment on the precipitation of Al3(Sc,
Zr) particles and the effect of these precipitates on hardening and softening processes of dilute
ternary Al-0.2wt.%Sc-0.1wt.%Zr alloy was investigated. Behaviour of two differently prepared
alloys (mold cast and prepared by powder metallurgy – PM) was investigated in as-prepared and in
cold rolled state. Both alloys exhibit the same peak age hardening, PM one reaches it already during
extrusion at 350°C. Both cold rolled alloys are highly resistant against recovery, which proceeds
without rapid hardness decrease at high temperatures. Evolution of hardness agrees well with that of
resistivity and with TEM observation.
357
Authors: M.A. Abdel-Rahman, N.A. Kamel, Abdullah A. Refeay, Emad A. Badawi
Abstract: Positron annihilation lifetime (PAL) measurement is one of the most important nuclear techniques used in materials science. Electrical measurements are also used in materials science. Both PAL and electrical measurements were used here to determine the activation energy of migration of dislocations in one of the most important engineering aluminum alloys: 2024. Samples of 25% deformed (thickness reduction) material have been used for these studies. The isothermal annealing measurements were performed at 583, 603, 623 and 643K for both techniques. The activation energy of migration of the dislocation was found to be equal to 1.24 ± 0.08eV by using PAL measurements and to 1.35 ± 0.01eV by using the electrical technique.
119
Authors: Fa Yu Wu, Yi Yong Wang, Wei Juan Li, Yan Wen Zhou, Jun Wei Zhang
Abstract: The micro-structure, the thermal and electrical transport properties, and their corresponding relationship of carbon micro-coils were discussed, based on the experimental results. The disordered micro-structure and the helical conformation of carbon micro-coils were responsible for the characteristic of their transport properties.
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