热处理对SiCp/Al复合材料强度和塑性的影响

采用粉末冶金法制备了d300 mm的15%SiCp/Al(体积分数)复合材料坯锭,研究了挤压态和T4态复合材料的力学性能和断裂特点,揭示了基体强度和颗粒开裂对复合材料强度与塑性的影响规律。结果表明:复合材料T4态拉伸强度保持在560 MPa的水平下,延伸率仍高达7%以上;与挤压态相比,T4态复合材料拉伸强度和屈服强度分别提高了68.5%和105%,但塑性保持在同一水平。断口观察表明:挤压态复合材料以基体断裂为主,而T4态复合材料除了基体断裂外,还存在SiC颗粒开裂现象;基体强度严重影响复合材料的断裂形式,颗粒开裂有利于提高复合材料的塑性。

Effect of heat treatment on strength and ductility of SiCp/Al composites

15%SiCp/Al composite billets with a diameter of 300 mm were fabricated by powder metallurgy method. Mechanical properties and fracture mechanisms of these composites as the extruded and in the T4 condition were investigated respectively. The effect of the matrix strength and particle fracture on the strength and ductility of the composites were presented. The results indicate that the composites in T4 condition gave an ultimate tensile strength of 560 MPa and elongation above 7%. 68. 5% increase in ultimate tensile strength and 105% increase in yield strength are obtained in the composites in the T4 condition compared to as-extruded, whereas the elongation and reduction in area of the composites in the T4 condition remain at the same level in comparison with the as-extruded. Fractographic analysis reveals that the failure in the matrix near the interface is predominant in the as-extruded composites, with a preference for failure in the matrix and fracture of SiC particles in the T4 condition. It is shown that the dominant failure mode of the composites are significantly affected by the matrix strength. The particle fracture is beneficial to the improvement of ductility of the composites.