高压扭转圈数对碳化硅颗粒铝基复合材料组织和性能的影响

采用高压扭转(high-pressure torsion,HPT)工艺,成功将8.75%体积分数SiC颗粒与Al的混合粉末制成金属基复合材料,并用金相显微镜、显微维氏硬度计、万能材料试验机和扫描电镜等,分析了扭转圈数对SiCp/Al复合材料的显微组织、显微硬度、拉伸性能和拉伸断口形貌的影响。结果显示,扭转圈数从0.5圈增加到4圈,基体的变形抗力降低,SiC颗粒在剪应力的作用下易于与基体协调变形,SiC颗粒分布均匀化程度显著提高;随着扭转圈数增加,试样所受到的剪切作用增大,极易引起位错的运动和增殖,基体晶粒得到细化,单位体积内的晶界增多,使试样显微硬度得到提高;扭转圈数越多,拉伸断口韧窝数量明显增多,且尺寸变小。

Effect of turning mumbers on microstructure and properties of SiCp/Al composite during high-pressure torsion

8.75vol%-SiC particles and Al powder mixtures were fabricated into metal matrix composites by high-pressure torsion(HPT).Influence of twisting numbers on microstructure,micro-hardness and tensile fracture surfaces of the composites was investigated under different conditions with optical microscope,Vickers hardness tester,universal material testing machine and scanning electronic microscope.The results show that,when twisting rounds increase from 0.5 to 4,matrix deformation resistance gets lower.So shear-strain would easily make SiC particles and Alumina-matrix coupled deformation,and SiC-particles distribution becomes homogeneous.With the increase of turning numbers,shear function becomes stronger and is easy to cause movements of dislocation,leading to the refinement of grain size,increase of grain boundaries per unit volume,so that the micro-hardness of sample gets improved.As twisting rounds increase,the dimples of tensile fracture surfaces greatly increase and the size of dimples becomes smaller.