挤压比对粉末热挤压制备铝基复合材料组织和力学性能的影响

Influence of extrusion ratio on microstructure and mechanical properties of Al matrix composites by hot extrusion of powders

采用粉末热挤压法制备硼酸镁晶须增强铝基复合材料,研究不同挤压比对挤压态复合材料微观组织和性能的影响。结果表明:随着挤压比的增加,硼酸镁晶须的排布取向逐渐趋向于材料的热挤压方向,晶须长径比有所减小,挤压比为25:1时,材料力学性能达到最佳值,屈服强度、极限拉伸强度及伸长率分别为113.5 MPa、230MPa和7.0%;拉伸强度(UTS)相比挤压态的6061铝合金和挤压比为9:1的复合材料分别提高了37%和25%;拉伸断口分析表明,材料的失效形式以6061Al基体的韧性断裂、晶须与基体间的脱粘以及晶须团聚体的脆性开裂3种形式为主。

The Mg 2 B 2 O 5 whisker reinforced Al matrix composites were fabricated using powder metallurgy routes. The effects of different extrusion ratios on the microstructure and tensile strength of composites were investigated. The results show that the alignment of Mg2B2O5 whisker along the extrusion direction is improved and the aspect ratio decreases with increasing extrusion ratio, meanwhile, the composites exhibit the best mechanical properties at the extrusion ratio of 25：1. Respectively, the yield strength, the tensile strength and the elongation of the extruded composites is 113.5 MPa, 230 MPa and 7.0%. The tensile strength increases by 37%and 25%, in comparison with the aluminum and composites. According to the analysis of fracture, the ductile failure of 6061Al matrix, the reinforcement fracture and the whisker-matrix interface debonding act as the main mechanism of fracture nucleation.