莫来石短纤维/Al-4.5Cu复合材料的力学性能与断裂特征

MECHANICAL PROPERTIES AND FRACTOGRAPH OF SHORT MULLITE FIBER/Al 4.5Cu COMPOSITE

采用挤压铸造法制造了莫来石短纤维／Ａｌ－４．５Ｃｕ复合材料，研究了不同挤压铸造工艺参数条件下其力学性能的变化规律和断裂特征。实验结果表明：随着凝固冷却速率的提高，莫来石短纤维／Ａｌ－４．５Ｃｕ复合材料的抗弯强度和弹性模量相应逐渐增大；另外，挤压铸造莫来石短纤维／Ａｌ－４．５Ｃｕ复合材料表现为脆性解理断裂，当凝固速率较大，复合材料强度较高时，断口中局部有莫来石短纤维拔出；同时，各种凝固冷却速率条件下，断裂面上均有少量韧窝存在。

The mechanical properties and fractograph of short mullite fiber reinforced Al 4.5Cu composite fabricated by squeeze cast method were studied in this paper. The experimental results showed that the bending strength and elastic modulus of the composite were improved both with increasing of solidification rate. The fracture surface of the composite showed a character of the brittle cleavage fracture. When the solidification rate was higher, a few mullite fibers were drawn out in certain areas of the fracture surface, and they represented the higher bending strength. In all cases of the solidificating rates studied, a few tough nests on the fracture surface of the composite were also observed.