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研究了一种无铼镍基单晶高温合金在1223 K、不同应变速率(5×10~(-4)s~(-1)、1×10~(-3)s~(-1)、5×10~(-3)s~(-1)、1×10~(-2)s~(-1))条件下的低周疲劳行为。结果表明:在四种应变速率条件下,合金均表现出循环稳定。随着应变速率的增加,合金的疲劳寿命逐渐增加,且其半寿命稳定滞后回线环内面积逐渐减少,表明低应变速率合金更容易积累蠕变塑性变形。疲劳裂纹源均萌生于试样表面,随着应变速率的增加,疲劳过程中产生的塑性变形越来越少,疲劳裂纹扩展区的面积逐渐增大。低应变速率时,较大的塑性变形导致合金取向发生明显的偏转,诱发多滑移系开动进而形成位错网;反之,高应变速率时,合金没有产生明显的塑性变形,只有单一方向的位错塞积形成位错束。
The effects of different strain rate (5 × 10 -4 s -1, 1 × 10 -3 s -1, 5 × 10 -3 s -1 and 1 × 10 -2 s -1, respectively. The results show that the alloys exhibit cyclic stability at four strain rates. With the increase of strain rate, the fatigue life of the alloy gradually increases, and its half-life stable hysteresis loop loop area gradually decreases, indicating that low strain rate alloys are more likely to accumulate creep plastic deformation. Fatigue crack sources were all sprouted on the surface of the specimen. With the increase of strain rate, the plastic deformation in fatigue process was less and less, and the area of fatigue crack growth area increased gradually. At low strain rates, large plastic deformation leads to significant deflection of the alloy orientation, inducing the multi-slip system to start to form a dislocation network. Conversely, at high strain rate, the alloy does not produce significant plastic deformation, only a single direction of the bit The staggered product forms a dislocation bundle.