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

 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（K_IC）,研究了微观结构与KIC之间的关系。

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

The Mo₃Si-Mo₅Si3 eutectic alloy , Mo₅Si3-MoSi₂ 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 buttonswere 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 Mo₅Si3 (D8m) / MoSi₂(C11b) with fine spacing of hundsed nanometer order was found in Mo₅Si3-MoSi₂ hypoeutectic alloy. The lamellarstructure did not change significantly before and after annealing in Mo₅Si3-MoSi₂ hypereutectic alloy. No lamellarstructure was observed in Mo₃Si-Mo₅Si3 eutectic alloy both before and after annealing. The fracture toughness( KIC) of alloys was determined by using Vickers indentation technique. The relationship between microstructureand KIC was investigated.