论文部分内容阅读
采用真空非自耗电弧熔炼法制备了Cr-12%Nb(原子分数,下同)和Cr-20%Nb 2种成分合金的纽扣锭,利用XRD,OM,SEM和EDS对电弧熔炼态纽扣锭不同位置的组织及其竞争生长进行了研究.结果表明:Cr-12%Nb合金纽扣锭底部为细小的离异共晶,中部和顶部则由粗大的初生Cr相和共晶组织(Cr_2Nb+Cr)组成.而Cr-20%Nb纽扣锭底部出现的是胞状层片共晶组织,层片间距为0.3μm,随着距纽扣锭底部距离的增加,冷却速率逐渐降低,凝固组织中相继出现Cr_2Nb板条枝晶和花瓣状Cr_2Nb枝晶.同时,基于TMK快速凝固共晶模型和BCT枝晶生长模型,通过计算并比较共晶组织和Laves相Cr_2Nb枝晶界面生长温度,借助最高界面生长温度判据,很好地解释了Cr-20%Nb合金凝固组织的演变及其形成原因.
The alloy ingots of Cr-12% Nb (atomic fraction, the same below) and Cr-20% Nb were prepared by vacuum non-consumable electric arc melting method. The effects of arc melting state button The results showed that the bottom of Cr-12% Nb alloy ingots was finely divided eutectic, the middle and top were composed of coarse primary Cr phase and eutectic (Cr 2 Nb + Cr ) .But the bottom of the Cr-20% Nb button ingot is the cell-like layer eutectic structure, the layer spacing of 0.3μm, with the distance from the bottom of the button ingot increases, the cooling rate gradually decreased, the solidification organizations have emerged Cr_2Nb Lamella dendrites and petal-shaped Cr_2Nb dendrites.At the same time, based on TMK rapid solidification eutectic model and BCT dendrite growth model, by calculating and comparing the growth temperature of eutectic microstructure and Laves phase Cr_2Nb dendrite interface, with the help of the maximum interfacial growth temperature It is well explained that the evolution of the solidified microstructure of Cr-20% Nb alloy and its formation causes.