(1. 江苏大学 材料科学与工程学院，镇江 212013；
2. 苏州明志科技有限公司，苏州 215217)
摘 要: 对不同工艺处理的铝硅合金ZAlSi7Cu4用自约束型热疲劳实验机进行20↔300 ℃、20↔350 ℃和20↔400 ℃的热循环试验，研究不同处理工艺对该材料热疲劳性能的影响及不同温度幅对裂纹生长的影响。通过光学显微镜和扫描电镜观察试样的热疲劳裂纹形貌, 研究合金热疲劳损伤机制。结果表明：该合金经过T6处理后比其他两种方式处理的合金具有更好的热疲劳性能；颗粒的位向会影响裂纹的扩展路径；在下限温度不变的情况下，随着上限温度的提高，ZAlSi7Cu4的3种状态合金的寿命都缩短。当下限温度为20 ℃时，合金在上限温度为300~350℃区间内的温度敏感性高于其在上限温度为350~400℃区间内的温度敏感性。
关键字: ZAlSi7Cu4；热疲劳；萌生；扩展；裂纹
（1. School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013, China;
2. Suzhou Ming Zhi Technology Company Limited, Suzhou 215217, China）
Abstract:The casting silumin ZAlSi7Cu4 that was treated with different technologies for heating processing was used to make a thermal cycle experiment at 20↔300 ℃, 20↔350 ℃ and 20↔400 ℃, respectively, on a self-restrict thermal fatigue experimental machine. The effect of thermal fatigue property caused by different technologies for heating processing and the effect of crack growth caused by different temperature breadths were studied. Optica1 microscopy (OM) and scanning electron microscopy (SEM) were used to examine the damage mechanisms of thermal fatigue. The results show that the sample with T6 treatment has better property than other two kinds of samples. The expansion path of crack can be influenced by the location of grains. With the increase of the maximum temperature, the lifespan of three kinds of alloys will decrease when the minimum temperature is fixed. In the interval of 300−350 ℃, the temperature sensitivity of the alloy is higher than that in the interval of 350−400 ℃ when the minimum temperature keeps at 20 ℃.
Key words: ZAlSi7Cu4; thermal fatigue; initiation; expansion; crack
