Low-Temperature Anelastic Property of Nanocrystalline Ag Fabricated by Gas Deposition Method

It was reported that the internal friction (Q-1) of nanocrystalline (n-) Au and n-Cu showed a rapid increase linearly with temperature above ~200 K. Since the rapid increase in Q-1 decreased with the progress in the grain growth, it was suggested that the anelasticity of grain boundaries in n-Au and n-Cu was thermally activated above ~200 K. In order to pursue the intrinsic behavior of the grain boundaries in n-metals, the internal friction of n-Ag was measured and the result was compared with those of n-Au and n-Cu. Similar to n-Au and n-Cu, Q-1 of n-Ag was also showed the increase linearly with temperature above ~200 K. However, the onset temperature for the linear increase in Q-1 of n-Ag was slight lower than those of n-Au and n-Cu and it can be attributed to the lower activation energy of the grain boundary self-diffusion in Ag.

据报道，纳米晶金（n-Au）与纳米晶铜（n-Cu）的内耗（internal friction, Q⁻¹）在约200 K以上随温度呈快速线性升高。随着晶粒长大（grain growth）进程推进，内耗的快速升高幅度逐渐减弱，据此推测纳米晶金与纳米晶铜的晶界（grain boundaries）滞弹性（anelasticity）在约200 K以上属于热激活（thermally activated）过程。为探究纳米晶金属（n-metals）晶界的本征行为，研究人员对纳米晶银（n-Ag）的内耗进行了测量，并将所得结果与纳米晶金、纳米晶铜的结果进行对比。与纳米晶金和纳米晶铜类似，纳米晶银的内耗Q⁻¹在约200 K以上同样随温度呈线性升高。不过，纳米晶银内耗Q⁻¹开始线性升高的起始温度略低于纳米晶金与纳米晶铜，该现象可归因于银的晶界自扩散（grain boundary self-diffusion）激活能更低。