Guo Jinpei, Zhong Minting, Zhou Wei, Zhang Yajiu, Wu Zhigang, Li Yingchao, Zhang Junsong, Liu Yinong, Yang Hong
School of Civil Engineering, Guangzhou University, Guangzhou 510006, China.
Department of Mechanical Engineering, The University of Western Australia, Perth, WA 6009, Australia.
Materials (Basel). 2021 Apr 30;14(9):2339. doi: 10.3390/ma14092339.
Isothermal annealing of a eutectic dual phase Ni-Mn-Sn-Fe alloy was carried out to encourage grain growth and investigate the effects of grain size of the γ phase on the martensitic transformation behaviour and mechanical properties of the alloy. It is found that with the increase of the annealing time, the grain size and volume fraction of the γ phase both increased with the annealing time predominantly by the inter-diffusion of Fe and Sn elements between the γ phase and the Heusler matrix. The isothermal anneals resulted in the decrease of the e/a ratio and suppression of the martensitic transformation of the matrix phase. The fine γ phase microstructure with an average grain size of 0.31 μm showed higher fracture strength and ductility values by 28% and 77% compared to the coarse-grained counterpart with an average grain size of 3.31 μm. The fine dual phase microstructure shows a quasi-linear superelasticity of 4.2% and very small stress hysteresis during cyclic loading, while the coarse dual phase counterpart presents degraded superelasticity of 2.6% and large stress hysteresis. These findings indicate that grain size refinement of the γ phase is an effective approach in improving the mechanical and transformation properties of dual phase Heusler alloys.
对共晶双相Ni-Mn-Sn-Fe合金进行等温退火，以促进晶粒生长，并研究γ相晶粒尺寸对合金马氏体转变行为和力学性能的影响。研究发现，随着退火时间的增加，γ相的晶粒尺寸和体积分数均随退火时间增加，这主要是由于Fe和Sn元素在γ相和赫斯勒基体之间的相互扩散所致。等温退火导致e/a比降低，并抑制了基体相的马氏体转变。平均晶粒尺寸为0.31μm的细γ相微观结构与平均晶粒尺寸为3.31μm的粗晶粒对应物相比，断裂强度和延展性分别提高了28%和77%。细双相微观结构在循环加载过程中表现出4.2%的准线性超弹性和非常小的应力滞后，而粗双相对应物的超弹性降低至2.6%，且应力滞后较大。这些发现表明，γ相的晶粒细化是改善双相赫斯勒合金力学性能和转变性能的有效方法。
