Solute redistribution and micromechanical properties of rapidly solidified multicomponent Ni-based alloys
Solute redistribution and micromechanical properties of rapidly solidified multicomponent Ni-based alloys
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DOI：
10.1007/s11431-018-9411-y
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发表时间：
2019-02
期刊：
影响因子：
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通讯作者：
N. Yan;Zihua Wang;Y. Ruan;B. Wei
中科院分区：
文献类型：
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作者：
N. Yan;Zihua Wang;Y. Ruan;B. Wei
用玻璃熔剂技术研究了四元合金Ni-5%Cu-5%Ag-5%Sn和五元合金Ni-5%Cu-5%Ag-5%Sn-5%Ge在快速枝晶凝固过程中的溶质捕获效应和显微硬度的提高。这两种合金的最大过冷度分别为310K(0.18Tl)和220K(0.13Tl)，快速凝固组织由α(Ni)和(Ag)固溶体相组成。随着过冷度的增加，α(Ni)相由粗大树枝晶向等轴晶转变。四元合金中α(Ni)相的枝晶生长速度大于五元合金中的枝晶生长速度，且随过冷度的增加先增大后减小。两种合金中α(Ni)相的维氏硬度均随过冷度的增加而提高，这主要是由于晶粒细化作用所致。同时，α(Ni)相中Cu、Sn、Ge元素的溶质俘获效应也是大过冷度下显微硬度提高的重要原因。Ge元素的加入通过溶质强化机制有效地提高了α(Ni)相的显微硬度。
The solute trapping effect and microhardness enhancement of quaternary Ni-5%Cu-5%Ag-5%Sn and quinary Ni-5%Cu-5%Ag-5%Sn-5%Ge alloys during rapid dendritic solidification are investigated by glass fluxing technique. In these two alloys, the experimental maximum undercoolings of 310 K (0.18TL) and 220 K (0.13TL) have been achieved and the rapidly solidified microstructures are composed of α(Ni) and (Ag) solid solution phases. The morphological transition from coarse dendrite into equiaxed structure is observed for α(Ni) phase with the increase of undercooling. The dendritic growth velocity of α(Ni) phase in quaternary Ni-5%Cu-5%Ag-5%Sn alloy is larger than that in quinary Ni-5%Cu-5%Ag-5%Sn-5%Ge alloy, which increases firstly and then decreases with the enhancement of bulk undercooling. The Vickers hardness of α(Ni) phase in these two alloys is enhanced with the increase of undercooling, which is attributed mainly to the grain refinement effect. Meanwhile, the solute trapping effect of Cu, Sn and Ge elements in the α(Ni) phase also contributes to the microhardness enhancement under large undercoolings. The addition of Ge element effectively increases the microhardness of α(Ni) phase due to solute strengthening mechanism.