Study On Microstructure And Properties Of SiC_P Reinforced Magnesium Matrix Composites Prepared By Rapid Solidification

The research object of the study was Mg-Zn-Y-Ce-Zr magnesium alloy.RE-4p-EX-CT66and RE-4p-EX-RS66 alloys were prepared using a process combined with rapid solidification（RS）and reciprocating extrusion（RE）.Then taken RE-4p-EX-CT66 alloy as a reference,comparative study of microstructure and mechanical properties were taken on RE-4p-EX-RS66alloy.Finally,RE-4p-EX-（xSiC_P/RS66）magnesium matrix composites with different content of SiC particles were fabricated by selecting RE-4p-EX-RS66 alloy as the matrix alloy and SiC particles with an average size of 0.6μm as the reinforcement.Microstructure and phase composition of magnesium alloy and magnesium matrix composites were observed by means of OM,SEM,XRD and TEM.Mechanical properties at room temperature as well as wear and friction and wear properties and damping capacity were also tested.The main conclusions are as follows:（1）RE-4p-EX-CT66 and RE-4p-EX-RS66 alloys mainly consist ofα-Mg,W and Mg₁₇Ce₂.But the grain size of RE-4p-EX-RS66 alloy is refined and the second phases distribute more uniformly.No new phases are found in RE-4p-EX-（xSiC_P/RS66）magnesium matrix composites,and they containα-Mg,W and Mg₁₇Ce₂and SiC particles.The structure of the magnesium matrix composites is uniform and the matrix has good combination with SiC particles.At the same time,intense dislocations can be observed around SiC particles.When the content of SiC particles is more than 5%,SiC particles are inclined to collect as cluster in the microstructure.（2）The hadness of RE-4p-EX-RS66 alloy obtaines 104.2 HV₅₀,and increased by 5.14%compared with RE-4p-EX-CT66 alloy.The hadness of magnesium matrix composites is higher than the matrix,and the hardness improves with the increase of SiC particles content.（3）Compared with RE-4p-EX-CT66 alloy,the tensile strength and yield strength of RE-4p-EX-RS66 alloy increase about 9.24%and 9.43%,while the elongation of RE-4p-EX-RS66 alloy decreases 2.32%against RE-4p-EX-CT66 alloy.The tensile strength,yield strength and elongation of RE-4p-EX-RS66 alloy obtain 422.05 MPa,418.71 MPa and10.52%,respectively.The composites exhibite better tensile strength and yield strength than the matrix,and the strength increases with the increase of SiC particles content,but the elongation decreses.The tensile fracture surface of the matrix shows a typical ductile fracture while the tensile fracture morphology of the composites exhibites plastic and brittle mixed fracture surface.（4）The wear resistence of the matrix increases with the addition of SiC particles.Therefor,the time to obtain stable wear stages of composites is shorter than that of the matrix.The wear mechanism of the matrix alloy transforms from abrasive wear to adhesion wear and delamination wear while the wear feature of the magnesium matrix composites changes from abrasive wear to adhesion wear with increase in applied load and sliding rate.（5）Under the same frequency at room temperature,when the strain amplitude is comparatively low,the damping capacity of the matrix alloy and magnesium matrix composites is independent of the stain amplitude.Meanwhile,the damping capacity of the matrix alloy and magnesium matrix composites increases rapidly with the increase of strain amplitude.（6）The results of damping-strain amplitude curves show that dislocation brought by SiC particles plays an important role in the increase of damping property of magnesium matrix composites,which shows good coincidence to the G-L dislocation damping medel.The main damping mechanism of the matrix alloy and magnesium matrix composites is the dislocation damping.