【作者】 邹欣伟；

【导师】 马勤；

【作者基本信息】 兰州理工大学 ， 材料学， 2008， 硕士

【摘要】 难熔金属硅化物具有高熔点、高强度、较低的密度以及良好的高温抗氧化性能，是非常具有潜力的高温结构材料，但是高的室温脆性阻碍了其工业应用。实践证明通过合金化和复合化以及先进的材料制备技术可以有效地改善高温金属间化合物的高的室温脆性和低的高温强度。本研究基于原位合成材料制备理念，设计Cu-Mo-Si、Co-Mo-Si和Ni-Mo-Si三种金属硅化物复相合金，以工业纯Cu、Co、Ni、Mo和Si元素粉体为原料，采用机械球磨活化配合以热压烧结的工艺方法（简称MA/HP工艺）原位反应合成制备金属固溶体弥散分布在金属硅化物基体中的复相合金材料。通过XRD、OM、SEM和EPMA等分析手段对实验所得合金进行了相组成、组织和相关力学性能的分析和表征，研究了韧性金属Cu、Co和Ni含量的变化对合金的微观结构和力学性能的影响。研究发现，通过本设计试验，Cu-Mo-Si、Co-Mo-Si和Ni-Mo-Si三种合金系金属硅化物合金均可以形成复相结构，其显微组织由Mo₅Si₃、Co₃Mo₂Si或Ni₃Mo₂Si金属硅化物和分布于其间的金属固溶体Cu（Mo，Si）、Co（Mo，Si）和Ni（Mo，Si）等物相组成，且各相分布均匀。Cu-Mo-Si系合金为Cu_ss/Mo₅Si₃复相结构；Co-Mo-Si和Ni-Mo-Si系合金其构成为Co基固溶体/Co₃Mo₂Si和Ni基固溶体/Ni₃Mo₂Si的复相结构。随着韧性金属Cu、Co和Ni含量的提高，各合金中的金属硅化物Mo₅Si₃、Co₃Mo₂Si和Ni₃Mo₂Si的含量减少，合金的硬度下降，但是合金的抗弯强度提高。Cu-Mo-Si系合金的抗弯强度由435．7MPa提高到784．8MPa；Co-Mo-Si系合金的抗弯强度由的335．7MPa提高到756．2Mpa；Ni-Mo-Si系合金由375．7MPa提高到1323．1MPa，可见韧性金属相Cu、Co和Ni有效的提高了合金的韧性。与此同时金属硅化物Mo₅Si₃、Co₃Mo₂Si和Ni₃Mo₂Si的高强度又可以使合金的保持较高的整体强度。另外，本研究还对三类复相合金材料的烧结行为进行了初步的分析和讨论，并建立了其致密化和金属硅化物相生成之间关系的简单模型。更多还原

【Abstract】 Transition metal silicides have been considered as promising candidate structural materials to be used at high temperatures due to their high melting points, high strength retention at high temperatures, reasonable densities and oxidation-resistant. However, its brittleness is the drawback hindering its industrial applications. The brittle behaviour can be reduced effectively by two different means: by alloying, or by microstructure control including in-situ composites. It is compared the microstructures and properties of silicides made hot-pressing（HP） method with those materials made by cast and reactive hot pressing without pre-alloyed mixture powder that the former has a density and homogeneous structure without segregation and crack.With the thought of in-situ compositing, Cu-Mo-Si composite silicide （with metal solid solution/metal silicid structure）, Co-Mo-Si and Ni-Mo-Si composite silicides （with metal solid solution/Laves phase structures） were prepared by MA+HP method using the raw materials of Cu, Co, Ni, Mo and Si powder. Then the composite silicides were characterized through XRD, OM, SEM and EPMA etc. The Cu-Mo-Si, Co-Mo-Si and Ni-Mo-Si ternary metal silicide alloys have a dense and uniform microstructure consisting of the metal silicids （Mo₅Si₃,Co₃Mo₂Si,Ni₃Mo₂Si） and the metal （Cu, Co, Ni） solid solution. With the increasing of the metal （Cu, Co, Ni） content, volume fraction of the metal silicids （Mo₅Si₃, Co₃Mo₂Si,Ni₃Mo₂Si） and the average hardness of the Me-Mo-Si （Me=Cu, Co, Ni） alloys decrease, nevertheless the bending strength of the alloys increase, 435.7⁷84.8MPa, 335.7⁷56.2Mpa, 375.7-1323.1MPa, respectively. Compared with the single-phase ternary metal silicides, the metal solid solution toughened metal silicide alloys have an excellent balance of strength and ductility, which was attributed to the effective toughening of ductile metal （Cu, Co, Ni） solid solution.Furthermore the sintering process of the Me-Mo-Si （Me=Cu, Co, Ni） metal silicde alloys was disgussed, the model of the sintering/metal silicide formation was builded.更多还原