金属钆中钨的演化迁移行为与调控

Evolution Migration Behavior and Regulation of Tungsten in Metallic Gadolinium

以氟化钆为原料,金属钙为还原剂,在真空感应炉内,用钙热还原和XRD法研究了金属钆中钨的来源、形态、分布、演化迁移行为和调控方法。结果表明,金属钆中钨主要来源于坩埚,以熔解态钨和夹杂物Gd_2(WO_4)_3两种形态存在。钨在金属钆铸锭的下表面中心区域位置发生偏聚,含量最高,上表面二分之一半径处含量最低。演化迁移行为主要有两条途径,单质钨经脱落、熔解、熔体中迁移再分配、铸模内向中心和底部迁移;单质钨被氧化为氧化钨后,进入熔体与钆结合为Gd_2(WO_4)_3、铸模内向中心和底部迁移。从钨坩埚致密性、熔炼氛围、炉内残余氧量、原辅料纯度和升降温制度等方面调控后,可获得平均钨含量为0.008%的金属钆。

The element source,shape,distribution,evolution migration behavior and regulation of W in metal gadolinium were studied via calcium thermal reduction and XRD applying GdF3 as raw materials and Ca as reductant in vacuum induction furnace.The results show that W mainly comes from crucible and exists in forms of melt state tungsten and inclusion Gd2（WO4）3.Content of W is the highest under surface of central region and is the lowest at 1/2 radius on ingot casting surface while W in metal gadolinium ingot casting appears partial poly.Evolutionary migration behavior of W is presented as two forms including shed,dissolution, migration redistribution in melt,and migration to bottom and center in cast mold,or W being oxidized to WO3 in form of Gd2（WO4）3 in melt,and migrating to bottom and center in cast mold.Gadolinium containing 0.008% W is obtained through regulating compactness of tungsten crucible,melting atmosphere,residual oxygen in furnace,purity of raw supplementary materials and regulation of temperature.