亚微米级Al_2O_3颗粒增强LD2铝合金复合材料的拉伸性能与强化机制

TENSILE PROPERTIES AND STRENGTHENING MECHANISMS OF LD2 Al ALLOY COMPOSITES REINFORCED WITH SUBMICRON Al_2O_3 PARTICULATES

为克服颗粒增强铝基复合材料的强度低、脆性大、机械加工难等问题，选用平均直径为０．１５μｍ，细小且接近圆形的Ａｌ２Ｏ３颗粒增强ＬＤ２铝合金，对其铸态材料和挤压材料的室温及高温拉伸性能进行了考察和组织分析，结果发现：颗粒尺寸小到亚微米级之后，材料的组织中极难观察到位错，增强机制也有所变化。在３０～４０％体积率的挤压材上得到了６４０～７６０ＭＰａ拉伸强度和８．６～２％的延伸率，增强率达到了２１２％，获得了高强度、高塑性、易加工性的复合材料。

In the present study, to overcome the shortcomings of particulate reinforced composites such as low strength, high brittleness and poor machinability, fine and near sphere particulates were used as reinforcement of LD2 Al alloy matrix composites, with their average size of only about 0.15μm. The tensile properties of as cast and extruded Al 2O 3 P/LD2 composites at room and elevated temperatures were measured. The microstructures of the composites were observed. The results showed that when the sizes of reinforcements were within submicron scale, no dislocation caused by mismatch of CTE was found in the matrix and the strengthening mechanism was changed. In the range of volume fraction of 30%?40%, the tensile strength and elongation of the composites were about 640?760MPa and 8.6?2% respectively, and the strengthening rate was 212%. Superior strength ductility and machinable property of the Al 2O 3 P/LD2 composites were obtained.