热处理保温时间对(TiC+TiB)/TA10复合材料组织特征的影响

Effect of Holding Time in the Course of Heat Treatment on Microstructure of(Ti C+Ti B)/TA10 Composite

采用粉末冶金与熔铸相结合的原位自生技术制备了(TiC+TiB)/TA10复合材料,研究了热处理保温时间对材料组织特征变化的影响。结果表明,复合材料在铸态和热处理状态下显微组织均由Ti基体、TiC和TiB增强相组成,且增强相在基体中分布较均匀。随着热处理保温时间的延长,铸态显微组织中呈枝晶状和条状的TiC增强相持续出现溶断现象,枝晶状和条状的TiC逐渐粒化;TiB出现碎化,碎化呈先增加后减弱的趋势;TiC内C含量逐渐增加,TiC内部产生Ti析出相,析出相的数量和尺寸逐渐增加。增强相产生的变化源于C、B和Ti原子的扩散和溶解机制。

(TiC+TiB)/TA 10 composite was in situ synthesized by a combination of powder metallurgy and meltingcasting techniques.The effect of duration of isothermal holding in the course of heat treatment on the micro structure of composite was investigated.The results reveal that TiC reinforcements with the morphologies of dendrite and bar in the as-cast sample were continuously dissolved and broken up at the root of dendrites and the neck of bar,becoming particulate shape during heat treatment,and with increasing the holding time,the particulate TiC reinforcements subsequently grew in equiaxial shape.TiB reinforcements were broken into small fragments at the holding time less than 8 h,but tended to grow up at the holding time greater than 8 h.Both the C content and the amount and size of Ti precipitate in TiC increased incrementally with the holding time.The variation of TiC and TiB reinforcements was caused by diffusion and dissolution mechanism of carbon,boron and titanium atoms.