复合场对TiB_2/AZ31复合材料组织和性能的影响

Effects of Compound Field on Microstructure and Mechanical Properties of TiB_2/AZ31 Composites

利用熔体内高温自蔓延反应制备了TiB2/AZ31复合材料,通过金相、扫描电镜、力学性能测试等技术考察了复合场对镁基复合材料铸态、均匀化态和轧制态微观组织和力学性能的影响。结果表明,TiB2/AZ31复合材料施加复合场后,α-Mg基体得到了显著的细化,铸态组织中的骨骼状β-Mg17Al12相渐渐向层片状共晶组织转变,并且使TiB2颗粒团簇的尺寸明显减小,均匀的分布于基体中。由于TiB2颗粒和复合场的引入,复合材料轧制态组织中切变带变得更窄更密集,TiB2颗粒团簇在流变应力作用下有少许的破碎,并沿着轧制变形流线分布。另外,复合材料的力学性能得到了明显改善,其中抗拉强度、屈服强度和延伸率分别达到351 MPa,315 MPa和7.7%。

The TiB2/AZ31 magnesium matrix composites were fabricated by the self-propagating high-temperature synthesis （SHS） reaction in the molten magnesium. The microstructures and mechanical properties were investigated using OM, SEM and electronic universal tester. The results show that with the application of compound field on the composites the microstructure of a-Mg is significantly refined, and the morphology offl-MglTAll2 varies from bone-like plates to lamellar precipitates. It is also shown that the compound field decreases the size of the clusters of TiB2 particles obviously and makes them distribute uniformly in the matrix. Due to the introduction of TiB2 particles and compound field, the shear bands in hot-rolled composites get slenderer and denser than the matrix. In the meantime, the clusters of TiB2 particles are broken slightly by flow stress and distribute along the metal deformation streamline. Accordingly, the tensile properties of composites are evidently improved, and the values of tensile and yield strength and elongation are 351 MPa, 315 MPa and 7.7%, respectively.