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研究了多元Al-7.5Si-4Cu合金在不同热处理状态下的热疲劳性能。结果表明,与铸态试样和淬火+时效热处理试样相比,T6态试样的力学性能最好,微观组织均匀,热疲劳性能最优良。当热循环次数≥10 000时,T6状态与淬火+时效试样由于Si相和A12Cu相的出现降低了裂纹扩展速率,铸态试样由于A12Cu相复熔球的存在导致裂纹扩展速率急剧上升。
The thermal fatigue properties of multivariate Al-7.5Si-4Cu alloy under different heat treatment conditions were studied. The results show that compared with the as-cast and quenched + aged heat-treated specimens, the T6 specimens have the best mechanical properties, uniform microstructure and the best thermal fatigue properties. When the number of thermal cycles ≥10 000, the crack growth rate was reduced due to the appearance of Si phase and A12Cu phase in T6 and quenched + aged specimens, and the crack growth rate sharply increased due to the presence of A12Cu reflowed balls.