等温退火和预压处理对Cu36Zr48Al8Ag8大块非晶合金力学性能的共同影响

摘要

研究等温退火和预压处理对 Cu36Zr48Al8Ag8大块非晶合金力学性能的共同影响。首先，将铸态样品在743 K 退火10 min，然后对退火后的样品进行预压处理，在800 MPa 压力下分别预压1、3、5和10 h。结果表明，退火处理后在非晶基体中形成了尺寸为10 nm 左右的纳米晶并极大地湮灭了自由体积，从而导致大块非晶合金完全丧失塑性。在800 MPa 下预压处理合适的时间(5 h)可以部分地恢复自由体积，进而部分地恢复大块非晶合金的塑性。而过长的预压时间(10 h)将导致自由体积的再次减小，主要源于纳米晶的过分长大。%The combined effects of isothermal annealing and pre-compression on the mechanical properties of Cu36Zr48Al8Ag8 bulk metallic glass (BMG) were investigated. The as-cast specimens were first annealed at 743 K for 10 min, and then pre-compressed under 800 MPa for 1, 3, 5 and 10 h, respectively. The results indicated that annealing resulted in the formation of nanocrystals with a diameter of ~10 nm in the amorphous matrix and a drastic decrease of the free volume, leading to complete loss of the plasticity of the BMG. Applying pre-compression under a stress of 800 MPa for a proper duration (5 h) resumed part of the lost free volume in the BMG matrix and therefore partially recovered the plasticity. A very long period of pre-compression (10 h) decreased the free volume again, which was caused by the excessive crystal growth.