热处理对Mo-Si系金属间化合物微观组织和断裂韧性的影响

The Effect of Heat-Treatment on Microstructure and Fracture Toughness of Intermetallics in Mo-Si System

以纯金属Mo与纯Si为原料,通过电弧熔炼法制备了Mo3Si Mo5Si3共晶,Mo5Si3 MoSi2亚共晶和过共晶Mo Si系金属间化合物。在1200℃分别对3种合金进行了12h、24h、48h和96h真空退火,观察层状结构在合金中的形成、变化及破坏。1200℃退火48h后,在Mo5Si3 MoSi2亚共晶合金中发现了发展完好的Mo5Si3(D8m)/MoSi2(C11b)层状结构,层间距为几百纳米;在Mo5Si3 MoSi2过共晶合金中,层状结构的层间距与体积百分含量在退火前后没有发生明显变化;在Mo3Si Mo5Si3共晶合金中始终未观察到层状结构的存在。通过压痕法测量了各合金的断裂韧性(KIC),研究了微观结构与KIC之间的关系。

The Mo_3Si-Mo_5Si_3 eutectic alloy, Mo_5Si_3-MoSi_2 hypoeutectic alloy and hypereutectic alloy of Mo-Si system were prepared by arc-melting high purity elements of Mo-99.9% and Si-99.99%. The arc-melting buttons were then annealed at 1200℃. The formation, alternation and destruction of lamellar structure were observed in alloys. After annealing at 1200℃ for 48h, the well-developed lamellar structure consisting of Mo_5Si_3(D8m)/MoSi_2(C11b) with fine spacing of hundsed nanometer order was found in Mo_5Si_3-MoSi_2 hypoeutectic alloy. The lamellar structure did not change significantly before and after annealing in Mo_5Si_3-MoSi_2 hypereutectic alloy. No lamellar structure was observed in Mo_3Si-Mo_5Si_3 eutectic alloy both before and after annealing. The fracture toughness (K_(IC)) of alloys was determined by using Vickers indentation technique. The relationship between microstructure and K_(IC) was investigated.