Cr、Yb合金化对Al-Zn-Mg-Cu-Zr合金组织和断裂特征的影响

Influence of Cr and Yb Alloying on the Microstructures and Fracture

摘要:

研究复合添加微量Cr、Yb、Zr对Al-Zn-Mg-Cu合金的显微组织和断裂特征的影响，分析其对合金韧化的作用机制。结果表明：在Al-Zn-Mg-Cu合金中复合添加Cr、Yb、Zr形成了含Cr、Yb、Zr的球形弥散相，这些均匀分布于基体上的弥散相能强烈钉扎位错和亚晶界，使基体保持形变回复组织，保持小角度晶界，抑制基体再结晶；T6态断裂机制主要为韧窝型穿晶断裂，与仅添加Zr相比，沿晶断裂抗力显著提高；晶界的无沉淀区(PFZs)较宽，且析出相在晶界呈明显不连续分布

Abstract:

The influence of complex Cr, Yb and Zr alloying on the microstructures and fracture characteristics of Al-Zn-Mg-Cu alloy has been investigated and the mechanism of toughening by adding Cr, Yb and Zr was analyzed. The results show that the Al-Zn-Mg-Cu alloy containing Cr, Yb and Zr may form the spherical dispersoids containing the Cr, Yb and Zr homogeneously distributed in the Al matrix, which can strongly pin the dislocation and subgrain boundaries, retain the deformation-recovery Al matrix with low angle boundary in the alloy and inhibit the recrystallization of Al matrix. By complex Cr, Yb and Zr alloying to Al-Zn-Mg-Cu alloy tempered as T6, the fractographs consist of dimple-type transgranular cracking with minor intergranular cracking. Compared with the Al-Zn-Mg-Cu-Zr alloy, the intergranular fracture resistance increases obviously, the precipitates free zone is wider with discontinuous distribution on the grain boundaries for the precipitates