单晶和多晶纯铝蠕变过程中的内耗

INTERNAL FRICTION OF MONO-AND POLY-CRYSTAL PURE ALUMINUM DURING CREEP TESTS

研究了单晶和多晶纯铝蠕变过程中的低频内耗。在单晶纯铝中观察到:内耗在蠕变初期单调下降,在蠕变第一阶段后期出现了一个显著的时间内耗峰,在蠕变第二阶段内耗趋于稳定值。多晶纯铝在类似实验条件下则不出现时间内耗峰。 文中分析了出现时间内耗峰的条件和原因,认为它是由于蠕变第一阶段中运动位错的阻尼系数逐渐增大所引起的。文中还从蠕变过程中位错运动的微观机制出发,推导出了蠕变过程中内耗的表达式,满意地解释了实验结果。

Internal friction of mono- and poly-crystal pure aluminum during creep at about IHz was studied. It was observed in monocrystal specimens that the internal friction decreased monotonously in the early stage of creep. A significant creep time-internal friction (Q^(-1)-t) peak was observed during the latter half of the primary creep under suitable experimental conditions. And the internal friction kept constant during the secondary creep. But no Q^(-1)-t peak was observed with polycrystal sample under similar experimental conditions. We suggest that the appearence of Q^(-1)-t peak is due to the increase of the damping coefficient of moving dislocations during primary creep. A specific dislocation mechanism is proposed, and the expression thereby deduced for the internal friction during creep is satisfactorily consistent with the experiments.