超声波搅拌时间对原位自生Mg2Si/Al基复合材料凝固组织和力学性能的影响

为了研究铝基复合材料的凝固组织和力学性能,采用超声波搅拌的方法制备了原位自生Mg₂Si/Al基复合材料.利用X射线衍射仪(XRD)、金相显微镜(OM)和扫描电子显微镜(SEM)分析其微观形貌,并通过硬度检测和拉伸试验测试其力学性能.结果表明:超声波搅拌不但能够细化初生Mg₂Si颗粒,改变凝固组织形貌,而且具有除气除杂功能,二者共同提高了Mg₂Si/Al基复合材料的力学性能;经过超声波搅拌的Mg₂Si/Al基复合材料与未经过超声波搅拌的Mg₂Si/Al基复合材料相比,抗拉强度与伸长率总体呈上升趋势,其断口形貌均为准解理面.在超声时间为40 s时,抗拉强度和伸长率达到最大值,分别为201 MPa和5.63%,相比未超声处理的Mg₂Si/Al基复合材料的抗拉强度和伸长率,分别增长了139.29%和178.71%;复合材料的硬度先升高后降低,超声作用时间为30 s时硬度最佳,为116.96(HB).

Effect of Ultrasonic Stirring Time on Solidification Microstructure and Mechanical Properties of In-situ Mg2Si/Al Composite

In order to investigate the solidified microstructure and mechanical properties of aluminum matrix composites,in-situ Mg₂Si/Al composite was prepared by ultrasonic stirring technique.XRD,OM and SEM were employed to analyze the microstructure of the composites.Mechanical properties of in-situ Mg₂Si/Al composite were tested via hardness test and tensile experiment.The results indicated that the ultrasonic stirring not only refined the primary Mg₂Si particle to improve the solidified microstructure,but also removed gas and impurity from the Mg₂Si/Al melt.The mechanical properties of the Mg₂Si/Al composites were therefore improved.The tensile strength and elongation of in-situ Mg₂Si/Al composite increased with ultrasonic stirring higher than without and the fracture morphology were quasi cleavage surface.Some conclusions were reached in this experiment:the tensile strength of the composite reached at 178 MPa and the elongation of the composite reached at 4.94% respectively as the ultrasonic stirring time was 40 s.The tensile strength and elongation with and without ultrasonic stirring of in-situ Mg₂Si/Al composite were compared which were increased by 139.29% and 178.71% respectively.Meanwhile,the hardness of the composite increased at first and then decreased,which reached the best(116.96) as the ultrasonic stirring time was 30 s.