研究了2种变形处理方式下的超细晶Cu-Cr-Zr合金从室温到600 ℃的拉伸性能、断口微观组织特征及其断裂机制. 结果表明: 经4道次等径弯曲通道挤压(ECAP)+时效+4道次ECAP变形处理的合金(No.1试样)的抗拉强度随拉伸温度的升高而降低, 室温时, 合金抗拉强度为577.17 MPa, 延伸率为14.6%; 在300 ℃开始发生动态再结晶软化, 抗拉强度迅速减小, 到600 ℃时抗拉强度仅为59.12 MPa. 经过8道次ECAP+时效变形处理的合金(No.2试样), 室温抗拉强度为636.71 MPa, 延伸率为12.1%; 从400 ℃开始析出相对晶界的钉扎作用开始逐渐减弱, 抗拉强度大幅降低, 600 ℃时的抗拉强度为65.20 MPa. No.2试样比No.1试样具有更好的室温性能和热稳定性. 2种方式处理下合金延伸率随拉伸温度的升高而升高, 在高温下都表现出超塑性. 高温拉伸断口微观形貌为大量密集、深入的韧窝, 其高温断裂机制为微孔聚集的韧性断裂.

Cu-Cr-Zr alloy usually applys to the complex environment at high temperature. The mechanical behaviors of alloy are different from the condition of normal temperature. At high temperature, grains and precipitates of ultra-fine grain Cu-Cr-Zr alloy become coarse and it would affect the hot deformation behavior of alloy. To solve the thermal stability of the ultra-fine grain materials, the grain growth mechanism and the driving force of ultra-fine grain materials must be studied, as well as trace elements on the thermal stability mechanism. Tensile properties, microstructure of fracture and fracture mechanism of ultra-fine grain (UFG) Cu-Cr-Zr alloy made by two different treatment methods were studied at the temperature range of room temperature to 600 ℃. The results show that the ultimate tensile strength (UTS) of alloys decreases with increasing temperature. The UTS and elongation of No.1 alloys are about 577.17 MPa and 14.6% at room temperature, respectively. And No.1 alloy start to occur dynamic recrystallization and UTS decreases fast at 300 ℃. The UTS of No.1 alloy are only 59.12 MPa at 600 ℃. The UTS and elongation of No.2 alloy are about 636.71 MPa and 12.1% at room temperature, respectively. The pinning effect by precipitation on grain boundary in the No.2 alloy begins to weaken at 400 ℃. The UTS of No.2 alloy decreases fast and are only 65.20 MPa at 600 ℃. Compared to No.1 alloy, No.2 alloy have better room temperature property and thermal stability. The elongation of all alloys increases with increasing temperature and show superplasticity on elevated temperature. The high temperature tensile fracture morphologies are an intense and deep dimple pattern. The high temperature fracture mechanism is ductile fracture by gathered microporous.