Development of Ni-Al Base Shape Memory Alloys with Enhanced

为了开发塑性增强的Ni-Al基形状记忆合金，研究了Ni-Al-Fe、Ni-Al-Mn和Ni-Al-Fe-Mn系合金的热加工性能、显微组织、形状记忆效应和力学性能。结果表明：（1）Fe和Mn的加入使合金中形成的少量面心立方相不仅对合金的热加工性能有显著影响，而且对合金的室温拉伸塑性也有显著影响。塑性的提高主要是由于β相共存对β相晶粒的改性。(2)在Ni-Al-Fe、Ni-Al-Mn和Ni-Al-Fe-Mn系中，以软化相为基体的韧性形状记忆合金是通过促进基体相晶界fcc相的形成而发展起来的。两相β + γ合金显示出高度的形状恢复，这取决于相的体积分数。在这些合金中，没有明确地检测到高于Ms的正常伪弹性行为。(3)可以通过调节β + γ两相区的退火温度来控制相变温度。Ni-Al-Fe和Ni-Al-Mn系形状记忆合金的最高工作温度分别为150 ℃和700 ℃。(4)虽然这些合金没有表现出完全的形状回复，但它们对于在较高温度下工作的新型形状记忆合金是有吸引力的。

In order to develop the Ni-Al base shape memory alloys with enhanced ductility, the hot workability, microstructure, shape memory effect and mechanical properties in the Ni-Al-Fe, Ni-Al-Mn and Ni-Al-Fe-Mn systems were investigated. The results obtained are as follows :(1) A small amount of fcc phase formed by the addition of Fe and Mn has a drastic effect not only on the hot workability but also on the tensile ductility at room temperature. The enhancement in ductility is mainly due to the modification of beta-phase grains by the coexistence of phase.(2) Ductile shape memory alloys based on the bate phase matrix in the Ni-Al-Fe, Ni-Al-Mn and Ni-Al-Fe-Mn systems have been developed by promoting the formation of fcc phase in the grain boundary of matrix phase. The two-phase beta+gamma alloys show high degree of shape recovery, which depends on the volume fraction of the phase. Normal pseudo-elastic behavior above Ms is not detected unambiguously in these alloys.(3) The transformation temperatures can be controlled by adjusting the annealing temperature in the beta+gamma two-phase region. The maximum operating temperatures for shape memory alloys in the Ni-Al-Fe and Ni-Al-Mn systems are 150ﾟC and 700ﾟC, respectively.(4) Although these alloys have not shown in the complete shape recovery, they are attractive for the new type of shape memory alloys which operate at rather high temperatures.