挤压包覆轧制对SiCP增强镁合金(AZ91)复合板显微组织和力学性能的影响

通过热挤压复合的方式将AZ91合金引入至SiC_P增强镁合金（AZ91）（SiC_P/AZ91）复合材料中，制备出厚度为2 mm的AZ91-（SiC_P/AZ91）复合板，研究了热轧对其显微组织和力学性能的影响规律。研究结果表明:AZ91的引入显著提高了SiC_P/AZ91的轧制成形能力。与AZ91层相比，SiC_P/AZ91层内晶粒尺寸小，硬度高。随轧制压下量的增加，AZ91-（SiC_P/AZ91）复合板晶粒尺寸变大，析出相数量减少且尺寸增大，导致硬度呈现下降的趋势。与挤压态AZ91-（SiC_P/AZ91）复合板相比，当压下量为50%时，轧制态AZ91-（SiC_P/AZ91）复合板屈服强度由272 MPa提高至341 MPa，抗拉强度由353 MPa提高至404 MPa。在拉伸过程中，因SiC_P与基体界面脱黏导致裂纹优先在SiC_P/AZ91层内萌生和扩展，AZ91层对微裂纹扩展具有一定的阻碍作用。 

Effect of extrusion-cladding rolling on microstructure and mechanical property of SiC_P reinforced magnesium alloy(AZ91)clad plate

The AZ91 alloy was introduced into SiCPreinforced magnesium alloy(AZ91)(SiCP/AZ91)composites by hot extrusion,and then the AZ91-(SiCP/AZ91)clad plate with the thickness of 2 mm was prepared in present work.After that,the microstructure and mechanical properties of SiCP/AZ91 clad plate influenced by hot rolling were investigated.The results indicate that the rolling formability of SiCP/AZ91 is significantly improved by introducing AZ91 alloy.As compared with AZ91 layer,the SiCP/AZ91 layer possesses much finer grain size and higher hardness.With the increase of rolling deformation amount,the grains in the AZ91-(SiCP/AZ91)clad plate grow up,the amount of precipitated phase decreases accompanied with the increase of its size.All above phenomena account for the decreasing micro-hardness.As compared with the extruded AZ91-(SiCP/AZ91)clad plate,the yield strength of rolled clad plate increases from 272 MPa to 341 MPa and the tensile strength increases from 353 MPa to404 MPa with the deformation amount of 50%.During the tensile process,the crack initiation and propagation occur preferentially in the SiCP/AZ91 layer due to the interfacial debonding between SiCPand Mg matrix alloy.However,the existence of the AZ91 layer will hinder the propagation of micro-cracks.