采用经典形核理论与负熵模型相结合,研究了多相竞争形核对竞争相的结构和过冷度的依赖性。通过对Fe70Co30合金熔体中的两个竞争相b c c相和f c c相的界面能、体积自由能差和临界形核功的计算,并结合已有的试验结果进行了分析。结果表明...采用经典形核理论与负熵模型相结合,研究了多相竞争形核对竞争相的结构和过冷度的依赖性。通过对Fe70Co30合金熔体中的两个竞争相b c c相和f c c相的界面能、体积自由能差和临界形核功的计算,并结合已有的试验结果进行了分析。结果表明,存在两相或多相竞争形核的金属熔体中存在着一个临界温度Tc。当熔体温度T>Tc时,稳定相将优先形核;而当熔体温度T<Tc时,亚稳相将优先形核。展开更多
采用熔融玻璃净化与循环过热相结合的方法,使原子分数Fe-30％Co合金获得了高达457 K 的大过冷度．系统考察了合金凝固组织随过冷度的演化规律．发现合金的凝固组织随过冷度的增大存在两次细化和一次粗化过程,即在小过冷度范围内粗大树...采用熔融玻璃净化与循环过热相结合的方法,使原子分数Fe-30％Co合金获得了高达457 K 的大过冷度．系统考察了合金凝固组织随过冷度的演化规律．发现合金的凝固组织随过冷度的增大存在两次细化和一次粗化过程,即在小过冷度范围内粗大树枝晶向粒状晶的转变和中等过冷度下局域定向枝晶的细化,而在大过冷度范围内随着亚稳枝晶核数目的增加,存在一个明显晶粒粗化的过程．展开更多
The high undercooling technique by molten glass slag purification and cyclical superheating in Ar atmosphere was applied to bulk Fe-B alloy melts. A hypercooling was achieved which suppressed the formation of stable p...The high undercooling technique by molten glass slag purification and cyclical superheating in Ar atmosphere was applied to bulk Fe-B alloy melts. A hypercooling was achieved which suppressed the formation of stable phase and consequently promoted the nucleation of metastable phase. Fe-17%B and Fe-20%B alloys were investigated, respectively. TEM and X-ray powder diffraction analyses verify the formation of metastable phase in the highly undercooled Fe-B alloy melts. Besides, the critical nucleation work of Fe2B and Fe3B phases was calculated to predict phase selection in the undercooled melts. The results show that the metastable phase formation is a function of the undercooling achieved prior to nucleation. And the amount of undercooling is an important factor in determining microstructural development by controlling phase selection in the undercooled melts.展开更多
文摘采用经典形核理论与负熵模型相结合,研究了多相竞争形核对竞争相的结构和过冷度的依赖性。通过对Fe70Co30合金熔体中的两个竞争相b c c相和f c c相的界面能、体积自由能差和临界形核功的计算,并结合已有的试验结果进行了分析。结果表明,存在两相或多相竞争形核的金属熔体中存在着一个临界温度Tc。当熔体温度T>Tc时,稳定相将优先形核;而当熔体温度T<Tc时,亚稳相将优先形核。
文摘采用熔融玻璃净化与循环过热相结合的方法,使原子分数Fe-30％Co合金获得了高达457 K 的大过冷度．系统考察了合金凝固组织随过冷度的演化规律．发现合金的凝固组织随过冷度的增大存在两次细化和一次粗化过程,即在小过冷度范围内粗大树枝晶向粒状晶的转变和中等过冷度下局域定向枝晶的细化,而在大过冷度范围内随着亚稳枝晶核数目的增加,存在一个明显晶粒粗化的过程．
基金Projects(50395103 50271057 50501020) supported by the National Natural Science Foundation of China
文摘The high undercooling technique by molten glass slag purification and cyclical superheating in Ar atmosphere was applied to bulk Fe-B alloy melts. A hypercooling was achieved which suppressed the formation of stable phase and consequently promoted the nucleation of metastable phase. Fe-17%B and Fe-20%B alloys were investigated, respectively. TEM and X-ray powder diffraction analyses verify the formation of metastable phase in the highly undercooled Fe-B alloy melts. Besides, the critical nucleation work of Fe2B and Fe3B phases was calculated to predict phase selection in the undercooled melts. The results show that the metastable phase formation is a function of the undercooling achieved prior to nucleation. And the amount of undercooling is an important factor in determining microstructural development by controlling phase selection in the undercooled melts.
