High Temperature Shape Memory Alloy Operated in New Mechanism

新发现Cu-Be合金在500 ~ 700 K的应力时效过程中，比普通形状记忆合金的时效温度高，发生了自发变形。在1000 K左右的分辨率下，自发变形得以恢复。为了弄清楚这种现象，人们做了各种实验，准备了悬臂梁和线圈的试件。实验结果表明，在时效过程中，当压应力作用于构件时，沉淀被延缓，而当拉伸应力作用于构件时，沉淀被促进。此外，γ′′和γ优先在压缩应力和拉伸应力作用的区域析出。γ′′析出和γ′析出分别引起自发收缩和自发延伸。因此，应力作用下的时效自发变形是由应力条件的交替引起的降水顺序的变化引起的。

It is newly found that a Cu-Be alloy spontaneously deforms during aging under stress where the aging temperatures are at a range of500 to 700 K that is higher than that of the ordinary shape memory alloy. The spontaneous deformation is restored by resolutionizing around 1000 K. In order to make clear the phenomenon, various experiments have been done preparing test pieces of cantilevers and coils. The experimental results yield that precipitation is retarded during aging when a compressive stress had been acted on an element of the body and, in turn, precipitation is promoted when a stretching stress had been acted on it. Furthermore, the γ" and γ preferencially precipitae at the regions where the compressive and stretching stresses had been acted, respectively. The γ" and γ precipitation causes the spontaneous shrinkage and elongation, respectively. Thus the spontaneous deformation by aging inder stress is coused by the change in precipitation sequence through the alternation of the stress conditon.