铸态Ti−25V−15Cr−0.3Si钛合金静态再结晶过程中的二次相析出位置及显微组织演变

摘要

利用热压缩和热处理实验研究铸态Ti?25V?15Cr?0.3Si钛合金的显微组织演变和二次相析出位置.研究在不同热处理温度和时间下晶粒的平均长宽比、平均面积和尺寸,分析变形量和退火参数对晶粒面积和尺寸的影响.结果表明,晶粒尺寸受变形量和退火时间影响显著,在950℃、变形量为30％、当退火时间从10 min增加至2 h时,晶粒明显长大;而当退火时间为2～4 h时,晶粒长大缓慢.此外,还观察到大量弥散质点以连续的链状存在,显微组织观察和TEM衍射花样分析证实沿着原始晶界析出的弥散质点为Ti5Si3相.%The microstructural evolution and precipitation location of the secondary phase of an as-cast Ti?25V?15Cr?0.3Si titanium alloy were investigated via isothermal compression experiments and heat treatment. The average aspect (length-to-width) ratio, average area and size of the grains at different heat treatment temperatures and holding time were analyzed and the effects of deformation and annealing time on the grain area and size were considered. It was found that the grain size was strongly influenced by the height reduction and holding time. Grain growth was significant when annealing time increased from 10 min to 2 h at 950 ℃ and height reduction of 30％; however, grain growth was minimal at annealing time between 2 and 4 h. Many dispersion particles were observed to form in continuous chains; the precipitation location was confirmed to be along initial grain boundaries, and the dispersion particles were identified to be Ti5Si3 phase by TEM.