Ni-Cr-W基高温合金近液相线细晶铸造(英文)  

Grain Refinement of Ni-Cr-W Based Superalloy by Near Liquidus Casting

作　　者：白坤[1] 胡锐[1] 李金山[1] 周廉[1,2] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,陕西西安710072 [2]西北有色金属研究院,陕西西安710016

出　　处：《稀有金属材料与工程》2014年第1期1-5,共5页Rare Metal Materials and Engineering

基　　金：Major State Basic Research Development Program of China(2011CB610404);Major National Science and Technology Projects(2009ZX04006-042)

摘　　要：通过近液相线‘铸造’的方法得到了细晶组织。采用感应加热方式将熔体处理至近液相线温度附近指定温度,然后让熔体直接在坩埚中炉冷。在具有一定形核过冷度的坩埚中得到了细晶组织并探索了晶粒细化的机制。可以将过冷熔体的凝固过程分为2个阶段:非平衡凝固阶段;近平衡凝固阶段。与近平衡凝固阶段相比,球形晶粒扰动发展的临界半径Rc在非平衡凝固阶段急剧减小。在非平衡凝固阶段,晶粒更倾向于以枝晶方式长大,晶粒的增殖通过枝晶的熔断产生并且最终的晶粒密度由该过程决定。在近平衡凝固阶段Rc急剧增大。Rc的增大与晶粒增殖阶段所确定大的核心密度导致凝固在球形晶粒扰动发展之前终止。因此,最终得到粒状晶粒形态。The grain refinement of Ni-Cr-W based superalloy was obtained by near liquidus casting. The melt was heated to the predetermined temperature near liquidus by induction heating and solidified directly in the crucible by furnace cooling. A fine-grained microstructure was obtained under a certain crucible nucleation undercooling and the related mechanisms are discussed. The solidification process of the undercooled melt is divided into two parts, a nonequilibrium process and a near-equilibrium process. The critical radius Rc for disturbance developing of spherical grains decreases greatly in the nonequilibrium process compared with the near-equilibrium process. Grains grow in dentritic manner in the nonequilibrium process and a crystal multiplication occurs in this process by remelting dentrite. Grain density is determined in the nonequilibrium process. In a near-equilibrium process, the disturbance of the spherical grains will develop with a larger Re. In situation of high nuclei density, decided by the nonequilibrium process, the larger Rc and the solidification terminates before disturbance developing. Thus, granular grains are obtained.

关 键 词：Ni-Cro-W基高温合金 近液相线铸造 晶粒细化 

分 类 号：TG29[金属学及工艺—铸造]