On the strength and stress-relaxation response of fine-grain Cu–42.2 at.%Zn–0.6 at.%Pb alloy polycrystals
On the strength and stress-relaxation response of fine-grain Cu–42.2 at.%Zn–0.6 at.%Pb alloy polycrystals
复制标题
细晶Cu-42.2 at.%Zn-0.6 at.%Pb合金多晶的强度和应力松弛响应
DOI：
10.1016/j.jallcom.2009.01.027
复制
发表时间：
2009
影响因子：
6.2
通讯作者：
M. S. Khiliji
中科院分区：
文献类型：
--
作者：
M. Z. Butt;M. S. Khiliji
在室温下进行拉伸试验，测量Cu-42.2at. % Zn-0.6at的强度和应力松弛响应。晶粒尺寸为5、7、9和11μm的%Pb多晶。强度参数屈服应力、极限抗拉强度和断裂应力随晶粒尺寸的增大而减小，符合Hall-Petch定律，而塑性随晶粒尺寸的减小而减小。恒应变下的应力松弛响应本质上是对数的。当初始应力水平σ 0允许恒应变松弛时，应力松弛量Δσ(t)=σo−σ(t)，应力松弛速率s=[d（Δσ）/dln(t)]随晶粒尺寸的增大而增大。而松弛速率ds/dσo的应力敏感性与晶粒尺寸无关。弛豫位错运动的本征能垒高度Uo为5.3eV，表明位错相交是应力弛豫的速率控制过程。在较宽的溶质浓度范围内，铜和Cu-Zn合金体系的应力松弛响应对合金的微观结构如溶质原子的空间分布模式、第二相粒子的分散等非常敏感。
Tensile tests were performed at room temperature to measure the strength and stress-relaxation response of Cu–42.2at.%Zn–0.6at.%Pb polycrystals of grain size 5, 7, 9 and 11μm. The values of the strength parameters, namely yield stress, ultimate tensile strength and fracture stress, were found to decrease with the increase in grain size in accordance with the Hall–Petch law, whereas the ductility decreased with the reduction in grain size. The stress-relaxation response studied at constant strain was logarithmic in nature. For a given initial stress level σo, from which relaxation at constant strain was allowed to start, both the amount of stress relaxed, Δσ(t)=σo−σ(t), and the magnitude of the stress-relaxation rate, s=[d(Δσ)/dln(t)], increased with the increase in grain size. However, the stress-sensitivity of relaxation rate, ds/dσo, was independent of the grain size. The intrinsic height of the energy barrier, Uo, to the movement of relaxing dislocations was found to be 5.3eV, which points to dislocation intersection as the rate-controlling process of stress-relaxation. A comparison of the available data for copper and Cu–Zn alloy system over a wide range of solute concentration shows that stress-relaxation response is sensitive to the alloy microstructure, e.g. mode of spatial distribution of solute atoms, dispersion of second-phase particles, etc.