V-5Cr-5Ti合金铸态组织中的第二相行为研究

Research of the Secondary Phase Behavior of As-cast V-5Cr-5Ti Alloy

摘要:

采用XRD、OM、SEM和TEM对V-5Cr-5Ti合金铸态组织结构进行分析。结果表明： 采用真空电子束熔炼制备的V-5Cr-5Ti合金铸态组织具有粗大的晶粒，晶粒内部存在以层状第二相堆垛成树枝状为特征的成分偏析区；金属钒和铸态V-5Cr-5Ti合金的晶格常数分别为0.30316nm和0.30375nm，V的单胞体积膨胀约0.58%；存在两种类型的第二相：1）短条状第二相，具有FCC结构，晶格常数为0.4182~0.4228nm；2）椭圆状第二相，具有FCC结构，晶格常数为0.4186~0.4242nm；V-5Cr-5Ti合金凝固过程中，首先Ti元素与C元素反应析出具有立方结构的亚稳间隙相（Ti2C）或V元素与C元素反应析出具有HCP结构的亚稳间隙相（V2C），随后原子发生相互取代，最终形成以Ti元素为主，V、Cr元素为辅，具有FCC结构的碳-氧-氮化物，化学式记为(Ti2-CON)。

Abstract:

The as-cast state microstructure was analyzed by XRD、OM、SEM and TEM. The results show that V-5Cr-5Ti alloy was fabricated by vacuum electron-beam melting ,it has coarse grain, the grain has the characteristics of dendritic crystal made by lamellar secondary phase. The lattice parameters of metal vanadium and V-5Cr-5Ti alloy is 0.30316nm and 0.30375nm, the swelling of V cell volume is 0.58%. There are two kinds of the secondary phase in as-cast alloy:1) Short strip secondary phase, has FCC structure, the lattice parameter is 0.4182~0.4228nm; 2) Elliptical-shaped secondary phase, has FCC structure, the lattice parameter is 0.4186~0.4242nm; In the process of solidification, Ti and C formed metastable interstitial phase (Ti2C), which has FCC structure, or V and C formed metastable interstitial phase (V2C), which has HCP structure; Then, atoms substituted by each other. Finally, the secondary phases are vanadium and chromium-alloyed precipitations of titanium oxycarbonitride, which chemical formula can be expressed as (Ti2-CON).