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利用真空非自耗电弧炉制备了较大成分范围的Nb-Ti-C合金,研究Ti、C含量变化对Nb-Ti-C合金组织结构和组成相点阵常数的影响。研究表明:合金凝固组织由Nbss和(Nb,Ti)C构成,且Nb-9Ti-8C和Nb-14Ti-12C合金存在Nb2C相,Nbss与(Nb,Ti)C两相具有洁净的界面。Nbss在C含量较低(4 at%)的合金中作为初生相析出,在C含量较高(8 at%~16 at%)的合金中做为二次结晶相析出,初生和次生的Nbss均呈枝晶或树枝晶生长,且在C含量一定时其枝晶尺寸随Ti含量的增加而增大。XRD和透射分析表明(Nb,Ti)C处于明显的C缺乏状态,C原子缺失引起fcc(Nb,Ti)C主衍射斑点之间出现衍射强度较弱的条状新斑点。Nb-21Ti-4C合金(Nb,Ti)C中C原子与金属原子的实际比值为0.65,并且(Nb,Ti)C中C原子缺失程度随Ti含量增加而增大。
A large range of Nb-Ti-C alloy was prepared by vacuum non-consumable electric arc furnace. The influence of the content of Ti and C on the lattice constants of the microstructure and composition phase of Nb-Ti-C alloy was studied. The results show that the solidified microstructure of the alloy is composed of Nbss and (Nb, Ti) C, Nb2C phase exists in the Nb-9Ti-8C and Nb-14Ti-12C alloys, and Nbss and (Nb, Ti) C phases have a clean interface. Nbss precipitates as the primary phase in the alloy with lower C content (4 at%) and precipitates as the secondary crystalline phase in the alloy with higher C content (8 at% ~ 16 at%). The primary and secondary Nbss All showed dendrite or dendrite growth, and the dendritic size increased with the increase of Ti content at a certain C content. XRD and transmission analyzes show that (Nb, Ti) C is in a markedly C-deficient state, and the absence of C atoms causes a new stripe-like spot with a weaker diffraction intensity between fcc (Nb, Ti) C main diffraction spots. The actual ratio of C atoms to metal atoms in Nb-21Ti-4C alloy (Nb, Ti) C was 0.65, and the degree of C atom deletion in (Nb, Ti) C increased with increasing Ti content.