摘要
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。
Nb-Ti-C alloys with a larger composition range were fabricated by a vacuum non-consumable arc-melting method.The effects of Ti and C contents on microstructure and lattice parameters of the alloys were investigated.The alloys consist of niobium solid solution( Nbss) and carbide of( Nb,Ti) C,and additional carbide of Nb2C is detected in Nb-9Ti-8C and Nb-14Ti-12C alloys.Nbss and( Nb,Ti) C has a clear interface.Nbss is precipitated as the primary phase in the alloy with C content of 4 at%.As C content of the alloys is in the range of 8 at% to 16 at%,( Nb,Ti) C is transformed to be the first precipitation.The primary Nbss and primary( Nb,Ti) C all grow into dendritic structure.XRD and TEM analyses show that( Nb,Ti) C carbide,is of poor carbon,which in turn leads to un-conspicuous strip diffraction pattern existing between the main diffraction pattern.The real atomic ratio of C and metal atom( Nb and Ti) in( Nb,Ti)C carbide is 0.65 for Nb-21Ti-4C alloy,and the C atom deficiency level increases with increasing nominal Ti content in the alloys.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2014年第7期100-106,共7页
Transactions of Materials and Heat Treatment
基金
国家自然科学基金(51004077)
