(Gr_p+SiC_p)/AZ91镁基复合材料的力学及耐磨性能

Mechanical Properties and Wear Resistance of(Gr_p+SiC_p)/AZ91 Magnesium Matrix Composites after Hot Extrusion

采用半固态搅拌技术制备出了5μm 10%Grp/AZ91、(5μm 5%Grp+5μm 5%SiCp)/AZ91和(5μm 5%Grp+10μm 5%SiCp)/AZ91(体积分数)镁基复合材料,并对其在300℃、0.05 mm/s的条件下进行了热挤压,研究了SiCp对挤压态复合材料显微组织、力学性能和耐磨性能的影响规律。结果表明,与Grp/AZ91相比,SiCp的引入导致基体晶粒尺寸增大和石墨颗粒碎化;随着SiCp尺寸增加,晶粒尺寸增大,石墨碎化现象更为显著。SiCp的加入提高了Grp/AZ91复合材料的硬度、抗拉强度和延伸率,随着SiCp尺寸增加,这种提升更为显著。SiCp的引入降低了Grp/AZ91复合材料的磨损率,但提高了摩擦系数,随着SiCp尺寸增加,磨损率进一步下降,摩擦系数进一步上升,磨损机制由剥层磨损转变为磨粒磨损。

Stir casting was employed to fabricate three kinds of magnesium matrix composites,5μm 10%Gr_p/AZ91,(5μm 5%Gr_p+5μm5%SiC_p)/AZ91 and(5μm 5%Gr_p+10μm 5%SiC_p)/AZ91.Subsequently the composites were subjected to hot extrusion at 300°C with a ram speed of 0.05 mm/s.And the effects of SiC_p on microstructures,mechanical properties and wear resistance were studied.The results show that the grain size of composites increases and the fragmentation of graphite of the three composites becomes more remarkable alon g with the SiC_p addition and its increasing size.Extruded 5μm 10%Gr_p/AZ91 composite possesses poor hardness,tensile strength and plasticity,but they are all improved after adding 5μm SiC_p,which are further enhanced by increasing the SiC_p size from 5μm to 10μm.And the wear rate of 5μm 10%Gr_p/AZ91 composite is decreased along with the adding and elevating size of SiC_p.On the contrary,the friction coefficient is significantly increased by enlarging the SiC_p size.The dominant wear mechanism of 5μm 10%Grp/AZ91 composite is delamination wear and it totally turns into abrasive wear in 10μm SiC_p hybrid reinforced composites by increasing the size of SiC_p.