原位合成TiB2/ ZL109 复合材料的高温蠕变行为

采用原位合成方法制备了TiB₂ 超细颗粒增强ZL109 复合材料, 对材料进行了高温拉伸蠕变实验。实验结果表明, 复合材料在高温恒应力条件下, 表现出高的名义应力指数和高的名义蠕变激活能, 优于纯Al 和ZL109 合金, 而且比常规外加颗粒复合材料具有更好的高温蠕变性能。引入门槛应力概念, 复合材料的蠕变实验结果能够用微观结构不变模型来解释, 说明复合材料的蠕变受到基体点阵扩散的控制。复合材料的蠕变断裂行为可以用Monkman2Grant 经验公式来描述, 蠕变断裂特征为延性断裂。

HIGH TEMPERATURE CREEP BEHAVIOR OF IN SI TU SYNTHESIZEDTiB2/ ZL109 COMPOSITE

The high temperature tensile creep tests were performed on TiB_2 ultrafine particulate reinforced ZL109 composite prepared by in situ formation technique. The composite exhibits high values of apparent stress exponent and apparent creep activation energy under constant applied stress at elevated temperatures. These values exceed greatly those for pure aluminum and ZL109 alloy. High temperature creep properties of the in situ TiB_2/ZL109 composite are better than those for conventional particulate reinforced composites. By introducing a threshold stress, the creep results of the composite can be explained by a microstructure invariant model, implying that creep of the composite is controlled by lattice diffusion in the matrix. The creep rupture behavior of the composite can be represented by Monkman-Grant empirical equation and the rupture characteristic of the composite is ductile fracture.