High Temperature Shape Memory Alloy Operated in New Mechanism

新发现Cu-Be合金在应力作用下时效过程中会自发变形，时效温度在500至700K范围内，高于普通形状记忆合金的时效温度。自发变形通过约1000K的分辨率得以恢复。为了弄清这一现象，已经进行了各种实验，准备了悬臂梁和线圈的测试件。实验结果表明，当压缩应力作用于主体的元件时，在老化过程中析出被延迟，反过来，当拉伸应力作用于其时，析出被促进。此外，γ”和γ分别优先在作用有压缩应力和拉伸应力的区域处析出。γ”和γ析出分别引起自发收缩和伸长。因此，应力条件下的时效自发变形是由应力条件的变化引起的析出序列的变化引起的。

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.