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采用自约束热疲劳试验机,对加入La的定向凝固Al-4.5%Cu合金进行热疲劳性能试验。结果表明,加入适量La对定向凝固Al-4.5%Cu合金的热疲劳性能有不同程度提高,其中,加入0.3%La的热疲劳试样疲劳性能较佳,达到热疲劳裂纹萌生所需的热疲劳循环次数最多;通过热疲劳循环次数与主裂纹长度的动态关系图,发现热疲劳裂纹的扩展有别于一般由机械交变载荷造成的常温疲劳,呈现先快后慢,阶段性扩展。
A self-restraining thermal fatigue tester was used to test the thermal fatigue properties of the Al-4.5% Cu alloy. The results show that adding proper amount of La improves the thermal fatigue properties of the Al-4.5% Cu alloy. The thermal fatigue resistance of the sample with 0.3% La added is better than that of the alloy without thermal fatigue. The results show that the thermal fatigue crack growth is different from the normal fatigue caused by the mechanical alternating load, which shows that the thermal fatigue crack grows slowly and gradually in stages after the thermal fatigue cycles and the main crack length.