稀土添加量对Ni80Cr20合金晶粒度、纯度和均匀性的影响

Effects of Rare Earth Addition on Grain Size,Purity and Uniformity of Ni80Cr20 Alloy

采用真空熔炼,结合锻造和轧制成形,制备了加入0%、0.2%和0.4%不同稀土的Ni80Cr20合金。借助光学显微镜、扫描电镜观察合金的显微组织,用能谱仪和电感耦合等离子发射光谱仪分析合金的成分,研究了稀土添加量对Ni80Cr20合金的晶粒度、纯净度和成分均匀性的影响,探讨了稀土元素对合金晶粒度和纯度的影响机理。结果表明:适量添加稀土,可细化Ni80Cr20合金晶粒,有利于净化合金熔体,改善合金成分分布均匀性;随着稀土加入量增加,合金的晶粒减小,含氧量和气孔减少,纯净度提高。当稀土添加量为0.4%时,合金的晶粒细小均匀,平均直径约为26.7μm,纯度达到99.95%。

Ni80Cr20 alloys with different addition of rare earth from 0 to 0.4% were melted in vacuum furnace and then forged and rolled. The microstructures were observed by using optical microscope, scanning electron microscope and the composition distributions were detected by energy dispersive spectrometry and inductive coupled plasma emission spectrometry. The effects of rare earth addition on the grain size, purity and uniformity of the NiSOCr20 alloy were discussed and effect mechanism was analyzed, It revealed that the addition of rare earth could refine the grains of NiSOCr20 alloy, clean-up molten metal. Ni and Cr element distribution became more uniform. With increase of rare earth addition from 0 to 0.4%, the grain size decreased, the oxygen content and gas holes became less, and the purity of the alloy was increased. When the addition of rare earth was 0.4%, the alloy had a uniform microstructure with a small grain size about 26.7 μm and its purity up to 99.95%.