金属玻璃温度依赖的拉压屈服不对称研究

Temperature-dependent yield asymmetry between tension and compression in metallic glasses

考虑静水应力对自由体积演化的影响,研究了金属玻璃在不同温度下的拉压屈服行为.结果表明,在拉伸和压缩载荷下,屈服强度均满足(T/T_g)^(1/2)的温度依赖关系;同时,在不同温度下,材料的压力敏感系数保持为常值0.1.随着温度的升高,压力对自由体积的影响逐渐降低,从而导致材料的拉压屈服不对称性逐渐趋于不显著.在高温下,显著的结构弛豫减缓了自由体积增长速率,从而抑制材料迅速屈服.这些结果将有助于更深入的认识金属玻璃屈服及其拉压不对称性的内在机理.

By taking the pressure effect into account in the free volume evolution,the yield asymmetry between tension and compression of metallic glasses（MGs） under different temperatures is investigated.The yield strength in MGs with a（T/Tg）1/2 temperature dependence is obtained for both tension and compression.The pressure-sensitive factor is derived to be a constant～0.1 within a broad range of temperatures.Furthermore,it is revealed that the declining effect of pressure on the free volume evolution causes a weaker tension-compression asymmetry with temperature increasing.The significant structural relaxation at high temperature slows down the free volume evolution and hinders the sharp yield.These results improve our understanding of the underlying mechanisms of the yielding and its asymmetry between tension and compression in MGs.