喷射沉积7090/SiCp复合材料SiC颗粒分布均匀性研究

制备了喷射共沉积及粉末冶金SiCp/7090Al复合材料,以不同的挤压比进行热挤压成形,研究了两种复合材料中SiC增强颗粒的分布特点。实验结果表明,沉积坯经过热挤压后,沿挤压方向SiC颗粒存在明显的带状分布特征,在横截面上具有同心圆环组织。而粉末冶金坯料经过热挤压后则避免了这一现象的产生,合理的热挤压工艺可以显著改善粉末冶金复合材料中的SiC增强颗粒的形貌,细化SiC增强颗粒的粒度。增强颗粒细化后得到的细小等轴颗粒更易随着基体的塑性流动而呈弥散均匀分布,改善或消除微区域内增强体颗粒的偏聚,减弱了偏聚的程度。室温力学性能测试结果表明,随着挤压比的增加,挤压态粉末冶金复合材料的抗拉强度由挤压比为11时的362.84MPa,增大到挤压比为25时的425.27MPa。

Distribution of SiC particles in multi-layer spray deposition 7090/SiCp Al matrix composites

The billet and powders of SiCp/7090Al composites were fabricated by the technique of multi-layer spray deposition,and different pressings were carried at different extrusion ratios,the effect of fabricating and working processes on the SiC particles distribution was investigated.Based on the microstructural examinations and mechanical properties of the obtained composite materials,banding of the silicon carbide particles parallel to the extrusion direction was observed along the pressing direction and a circle distribution for SiC particles around the central axis of the bars for the as-deposited billet after extruded.While we do not observe this phenomena for the composite powders after hot extrusion,an uniform distribution of the reinforcing particles in the aluminum matrix was revealed,the shape of reinforcements was remarkably improved.By using the low ductility and great distortion of matrix,the size of reinforcements can be reduced and produce fine axial symmetrical reinforcements which can more easily distribute homogeneously with the matrix's flow.It can also improve or eliminate the gather of reinforcement s at micro-areas in the matrix or mostly depress the gather degree of reinforcements.Ambient tensile tests made it possible to demonstrate that all these properties change along with the extrusion ratios change,the ultimate tensile strength increases along with the increase of the extrusion ratio from 362.84MPa for 11 to 425.27MPa for 25.