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用电化学方法分离出锆-4合金中第二相,研究了不同热处理制度对第二相结构和成分的影响。锆-4合金经1050℃β相加热空冷后,析出的第二相为立方结构的Zr(Fe,Cr)_2,Fe/Cr比值在2.1～2.5之间。试样重新在600～800℃下加热3h,晶体结构不发生改变,只是Fe/Cr比值逐渐降至1.9;但在700～800℃下加热后,有少量的六方结构Zr(Fe,Cr)_2第二相析出。生产厂提供的锆-4板中第二相是六方结构的Zr(Fe,Cr)_2,重新在700～800℃加热3h,晶体结构不发生变化,Fe/Cr比值由1.9降至1.5左右。这说明在重新加热时,第二相中的Fe和Cr与周围基体中的Fe和Cr会相互扩散置换。试样从β相冷却析出第二相时,Fe原子的扩散比Cr原子快;Cr原子在六方晶格Zr(Fe,Cr)_2中的固溶度比在立方晶格Zr(Fe,Cr)_2中的大。由于这些原因造成了第二相成分随热处理制度不同而变化的现象。
The second phase of zirconium-4 alloy was separated by electrochemical method and the influence of different heat treatment systems on the structure and composition of the second phase was studied. Zirconium-4 alloy is cooled by β-phase heating at 1050 ℃, and the second phase precipitated is Zr (Fe, Cr) _2 with cubic structure and the ratio of Fe / Cr is between 2.1 and 2.5. The sample was re-heated at 600-800 ℃ for 3h, the crystal structure did not change, but the Fe / Cr ratio gradually decreased to 1.9. However, after heating at 700-800 ℃, a small amount of hexagonal Zr (Fe, Cr) 2 The second phase precipitation. The second phase of the zirconium-4 plate provided by the manufacturer is a hexagonal Zr (Fe, Cr) _2, which is heated again at 700-800 ° C for 3h, the crystal structure does not change, and the Fe / Cr ratio is reduced from 1.9 to 1.5. This shows that upon reheating, the Fe and Cr in the second phase and the Fe and Cr in the surrounding matrix diffuse and displace each other. When the sample precipitates from the β phase, the diffusion of Fe atoms is faster than that of Cr atoms. The solubility of Cr atoms in the hexagonal Zr (Fe, Cr) _2 in the big. For these reasons, the second phase composition changes with the heat treatment system.