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采用XRD、OM、SEM和TEM对铸态V-5Cr-5Ti合金退火处理后组织结构进行分析。结果表明:在退火过程中,随着退火温度升高,铸态V-5Cr-5Ti合金第二相发生分解、扩散、聚集。第二相形貌由层状组成树枝状第二相转变成针状组成团聚状第二相。随着时间的推移,针状第二相尺寸发生了粗→细长→短粗的转变。1100℃,2h退火处理后V-5Cr-5Ti合金组织中存在3种类型的第二相(1)条状第二相,宽度为80~100 nm,长度为几个μm,化学式记为V_2-CO。(2)针状第二相,具有fcc结构,晶格常数为0.4193~0.4256 nm,该第二相在晶内或平行或垂直排列。(3)椭圆状第二相,具有fcc结构,晶格常数为0.4203~0.4268 nm。铸态V-5Cr-5Ti合金退火过程中,树枝状第二相首先发生分解、扩散,随后合金元素脱溶沉淀,形成以针状第二相为特征的团聚状第二相。该第二相是以Ti、V元素为主,Cr元素为辅,具有fcc结构的、稳定的碳-氧-氮化物,化学式记为(TiV)-CON。
The structure of as-cast V-5Cr-5Ti alloy was analyzed by XRD, OM, SEM and TEM. The results show that the second phase of as-cast V-5Cr-5Ti alloy decomposes, diffuses and accumulates with the increase of annealing temperature during the annealing process. The morphology of the second phase was changed from dendritic second phase to acicular second phase. With the passage of time, the size of acicular second phase changed from coarse to thin to short. There are three kinds of second phase (1) strip second phase in the V-5Cr-5Ti alloy after annealing at 1100 ℃ for 2h, the width is 80 ~ 100 nm and the length is several μm, the chemical formula is V_2- CO. (2) A second acicular phase having an fcc structure with a lattice constant of 0.4193-0.4256 nm, the second phase being arranged in the crystal either in parallel or in the vertical direction. (3) an elliptical second phase having a fcc structure with a lattice constant of 0.4203 to 0.4268 nm. During the annealing of the as-cast V-5Cr-5Ti alloy, the dendritic second phase decomposes and diffuses firstly, then the alloying elements are desolvated and precipitated to form the second phase with the acicular second phase. The second phase is a stable carbon-oxygen-nitride with fcc structure, which is dominated by Ti and V elements and supplemented by Cr elements and has the chemical formula (TiV) -CON.