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Ni-Ni3Si作为一种高强度和耐腐蚀的新型金属基复合材料,在航空航天等高温结构领域有潜在的应用前景。本研究采用布里奇曼定向凝固技术制备的Ni-Ni3Si共晶复合材料的定向生长特性。研究表明,未凝的组织为树枝晶组织,经过定向凝固后,初始过渡区粗大的Ni3Si相领先共晶组织生长,稳态生长区的组织为典型的层片共晶组织。采用XRD和EDS技术系统地分析了Ni-Ni3Si共晶的相分布规律,表明定向凝固后的Ni-Ni3Si复合材料由Ni相、Ni3Si相和Ni31Si12相三相组成,其中的Ni31Si12为亚稳相,是凝固过程中由β2-Ni3Si相的共析分解反应所形成的。此外,在凝固过程中出现了共晶的层片间距调整。
As a new type of high strength and corrosion resistant metal matrix composite, Ni-Ni3Si has potential applications in the field of high temperature aerospace structures. In this study, directional growth characteristics of Ni-Ni3Si eutectic composites prepared by Bridgman directional solidification technique were investigated. The results show that the undenatured structure is dendritic structure. After directional solidification, the coarse Ni3Si phase in the initial transition zone leads the eutectic structure. The steady state growth zone is a typical lamellar eutectic structure. The phase distribution of Ni-Ni3Si eutectic was systematically analyzed by XRD and EDS techniques. The results show that the Ni-Ni3Si composite after directional solidification consists of Ni phase, Ni3Si phase and Ni31Si12 phase. Ni31Si12 is metastable phase, It is formed by eutectoid decomposition reaction of β2-Ni3Si phase during solidification. In addition, eutectic layer spacing adjustment occurred during solidification.