AlN颗粒在不同铝合金中的增强行为

LD2为了解AlN颗粒对不同强度等级的铝合金的增强效果及机制 ,对 40 %体积分数的AlN颗粒增强 10 70、10 6 1、LY12铝合金复合材料拉伸前后的微观组织进行了观察 ,发现拉伸前在基体中存在由热错配引起的高密度位错 ,在AlN颗粒的内部也存在大量的位错 ,拉伸后基体中的位错增殖 ,同时 ,AlN颗粒中的位错亦增多 .力学性能的测试结果表明 ,AlN颗粒对低强度、高塑性的L3纯铝增强率最高 ,中等强度、较高塑性的LD2铝合金不仅有较高的增强率 ,而且保持了一定的塑性 .AlN颗粒对基体的这种选择性主要与AlN颗粒在拉伸过程中产生微量变形 ,从而松弛部分界面应力有关 .LY12基体的塑性较低 ,易产生低应力断裂 ,因此 ,AlN颗粒的增强作用难以得到充分发挥 .

Strengthening behavior of AlN particles in different aluminum alloys

In order to investigate the strengthening effect and mechanism of AlN particles in aluminum alloys with different strength levels the microstructure of AlN particles reinforced 1070, 6061 and 2024 aluminum alloy based composites (V f=40%) were observed before and after tension. The high density of dislocations generated by thermal misfit were found in both matrix and AlN particles before tension. After tension, the dislocations in the matrix and AlN particles propagate at the same time. The results of mechanical properties show that amony three composites fabricated with various aluminum alloys, the highest strengthening rate can be obtained in the 1070 pure aluminum with low strength and high plasticity, and high strength and plasticity can be obtained in the 6061 alloy with medium strength and relativly higher plasticity. This may be related to the fact that AlN particles yield some micro-deformation during tension and relax some internal stress near the interface. Due to the low plasticity, AlNp/2024 composite tends to fracture at low stress and it is very difficult for AlN particles to exploit their strengthening effect.