耐热低膨胀高硅铝合金的成形与性能

利用超声振动半固态流变压铸成形的方法制备出含20%Si的AlSiCuMgNiRE合金,研究了这种合金的组织、高温性能及热膨胀性能。结果表明,P与稀土复合变质的高硅铝合金,300℃的高温抗拉强度达到167 MPa,室温强度达到310 MPa;25~300℃内的热膨胀系数为17.4×10-6(1/℃)。添加2%Fe的高硅铝合金,由于针状富Fe相割裂基体,力学性能大幅度降低。而通过超声处理可改变富Fe相的形态,其室温及高温力学性能提高。

Formation and Properties of Low Expansive and Heat-Resistant Aluminum Alloy with High Silicon Content

An AlSiCuMgNiRE aluminum alloy with 20% Si was fabricated by semi-solid rheo-diecasting method, in which slurry was made with ultrasonic vibration, and the microstructure, mechanical properties at high temperature and thermal expansion of this alloy were studied. The results show that, if it is complex modified with P and RE, the high temperature tensile strength at 300 ℃ of this high Si aluminum alloy reaches 167 MPa, the tensile strength at room temperature is about 310 MPa, and the thermal expansion coefficient from 25 ℃ to 300 ℃ is 17.4×10~(-6) (1/℃ ). When 2%Fe was added, the mechanical properties were greatly decreased because of the cutting effect of needle-shape Fe-containing compound on the matrix. However, the tensile strengths at room and high temperatures were remarkably increased through changing the shape of Fe-containing compounds by ultrasonic vibration treatment.