稀土Ce对Al-Cu4.5%合金热疲劳性能的影响

Effect of RE cerium on thermal fatigue property of Al-4.5%Cu alloy

在接近材料实际工况的实验条件下,以铝铜合金(Cu4.5%)为研究对象,用自约束型热疲劳实验机对铈加入量不同的合金,进行了热疲劳实验以及热疲劳裂纹萌生及扩展规律的研究。结果表明:在裂纹萌生阶段,不加铈的铝铜合金的裂纹萌生速度明显大于加铈的合金;在裂纹扩展阶段,不加铈的铝铜合金裂纹扩展速度仍是最快。加入0.5%Ce的合金在裂纹形成后期扩展速度明显加快,这是因为合金中出现针状富稀土相,这种针状相割裂了基体,使得合金力学性能降低、热疲劳抗力下降。加入0.3%Ce的合金不论在裂纹萌生阶段还是裂纹扩展阶段,其热疲劳抗力都优于其它成分的合金。

Under the experimental condition similar to practical working environment, thermal fatigue test of Al- 4.5%Cu alloy with different Ce additions was carried out on self-restrict thermal fatigue experimental machine. And the initiation and propagation of thermal fatigue crack were studied. The results show that during the initiation of thermal fatigue crack, the velocity of crack initiation of Al-4.5^Cu alloy without Ce addition is obviously greater than that of alloy with Ce addition, and during the period of crack propagating, the largest propagation velocity occurs under the former condition. After the initiation of crack, the crack propagating of alloys with 0.5%Ce addition is accelerated evidently because of the appearance of needle rear earth rich phases which dissever the matrix and lead to the decrease of mechanical properties and thermal fatigue resistance. The thermal fatigue resistance of alloy with 0.3%Ce addition is superior to that of other alloys, during crack initiating and propagating.