|Cite this article as:|
|Yujiao Wang, Yun Zhang, and Haitao Jiang, Tension-compression asymmetry and corresponding deformation mechanism in ZA21 magnesium bars with bimodal structure, Int. J. Miner. Metall. Mater.,(2021). https://doi.org/10.1007/s12613-021-2388-x|
We investigated the asymmetric tension-compression (T-C) behavior of ZA21 bars with bimodal and uniform structures through axial tension and compression tests. The results show that the yield strengths of bars having bimodal structure are 206.42 and 140.28 MPa under tension and compression, respectively, which are higher than that of bars having uniform structure, that is, tensile and compressive yield strength of 183.71 and 102.86 MPa, respectively. Prismatic slip and extension twinning under tension and basal slip and extension twinning under compression dominate the yield behavior and induce the T-C asymmetry. However, due to the basal slip activated in fine grains under tension and the inhibition of extension twinning by fine grains under compression, the bimodal structure possesses a lower T-C asymmetry (0.68) compared to the uniform structure (0.56). Multiple extension twins occur during deformation, and the selection of twin variants depends on the Schmid factor of the six variants activated by parent grains. Furthermore, the strengthening effect of the bimodal structure depends on the grain size and the ratio of coarse and fine grains.