Microstructural evolution of a commercial pure Ni processed by ambient and cryogenic rolling
LI Yan1, NI Song1, CHEN Gang2, SONG Min1
1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China; 2. School of Materials Science and Engineering, Hunan University, Changsha 410082, China
Abstract The hardness and microstructural evolutions of a commercial pure nickel subjected to rolling (thickness reduction is 20%, 40% and 60%, respectively) at room temperature and cryogenic temperature were investigated using transmission electron microscope (TEM), optical microscope and Vickers microhardness testing. The results show that, the dislocation slip dominates the deformation process at small strain when the sample is rolled at ambient temperature. As the strain increases, dislocation and twins appeared to coordinate the deformation. When the sample is rolled at cryogenic temperature, a larger density of dislocations and more twins can be observed at small strain, compared to the sample rolled at the ambient temperature. In addition, the grain refinement process of the cryogenically treated sample is much faster than the room temperature rolled sample because the interaction between dislocations and MBs/twins is more severe due to the low speed of dynamic recovery. Both samples have a sharp hardness increase at small strain, then the hardness increases softly with increasing the strain. The cryogenically treated sample always has a higher hardness due to a high density of the dislocations.
LI Yan,NI Song,CHEN Gang, et al. Microstructural evolution of a commercial pure Ni processed by ambient and cryogenic rolling[J]. Materials Science and Engineering of Powder Metallurgy, 2018, 23(6): 575-581.
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2018, Vol. 23 
