短纤维增强铝基复合材料回蠕变与再蠕变行为研究

Creep experiments with sudden load changes were performed on Al alloy reinforced with alumna short fibers. Upon unloading, an immediate strain response is observed followed by a continuous back creep process. It was found that the transient strain response is just an elastic contraction of the composite, which objects to the results in the literatures which were obtained with composite as well as pure metal and alloys. The preceding creep history at major stress has influence on the back creep behavior. Stress change processes make no effect on the minimum creep rate of the main creep. The backflow strain accumulated in each unloading transient is related to the main creep time and also to the main creep strain. By fractography, the occurrence of a large number of voids, microcracks around fibers or along crystal interfaces, broken fibers, and debonding between fibers and matrix is found in the composite materials after creep fracture. It ultimately causes the failure of the composites in creep.

通过对短纤维增强铝基复合材料在变载,变温条件下蠕变过程的研究,确定相应于不同载荷变化的复合材料变载回蠕变特性规律和再蠕变机制,提出热循环条件下复合材料蠕变过程机理,揭示蠕变变形中复合材料微观组织结构的变化以及蠕变变形的相互作用机制.研究方法和手尉哂邢冉院投捞匦?研究成果将为金属基复合材料的应用提供理论基础....