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为了解高温退火前后V-4%Cr-4%Ti(记为V-4Cr-4Ti,下同)合金微观组织结构的变化,将合金在1000～1400℃,1×10-2Pa条件下退火不同时间(1h或3h)后,利用透射电子显微镜(TEM)分析了退火前后合金中位错、层错及孪晶的形态。分析结果表明,铸态合金中含有少量的层错和孪晶,但位错密度较高。高温退火后合金中的位错密度降低,层错、扩展位错的密度增加。孪晶密度随退火温度和退火时间的增加而增加。1200℃退火合金中的层错呈现规则的平行排列,层错使得基体衍射点发生分裂;孪晶的孪生面为钒的{211}晶面。在1300℃/3h退火合金中观察到了由大量微孪晶和位错组成的类“马氏体”结构。
In order to understand the microstructure changes of V-4% Cr-4% Ti (denoted V-4Cr-4Ti, the same below) before and after high temperature annealing, the alloys were annealed at 1000 ~ 1400 ℃ and 1 × 10-2Pa After 1 h or 3 h, the morphology of dislocations, stacking faults and twins in the alloy before and after annealing were analyzed by transmission electron microscopy (TEM). The results show that the as-cast alloy contains a small amount of stacking faults and twins, but the dislocation density is higher. The dislocation density in the alloy decreases after high temperature annealing, and the density of layer faults and extended dislocations increases. Twins density increases with annealing temperature and annealing time. The stacking faults in the annealed alloy at 1200 ℃ have regular parallel arrangement, and the stacking faults lead to the splitting of the diffraction spots on the substrate. The twin planes of the twins are the {211} crystal planes of vanadium. In 1300 ℃ / 3h annealed alloy was observed by a large number of micro-twins and dislocations composed of the class “martensite ” structure.