AMORPHIZATION TRANSFORMATION BY MECHANICAL ALLOYING IN THE Mo-Si SYSTEM

作     者：M.W. Li R.Z. Tang and W.X. Li (Department of Materials Science and Engineering, Central South University of Technology, Changsha 410083, China) 

作者机构：Central South Univ of Technology Changsha China 

出 版 物：《Acta Metallurgica Sinica(English Letters)》 (金属学报（英文版）)

年 卷 期：1997年第10卷第2期

页      面：134-140页

核心收录：

学科分类：0810[工学-信息与通信工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0812[工学-计算机科学与技术（可授工学、理学学位）] 

主　　题：mechanical alloying molybdenum silicide amorphization transformation 

摘      要：Starting from elemental powders, complete MoSi2 powder forms abruptly between 3.5and 4 h during mechanical alloying (MA) of the Mo-66 at.% Si powders. Continuous milling of this MoSi2 Phase leads to a nanocrystalline powder and amorphizationtransformation takes place after 100 h milling. Howeven MA of the Mo-37.5 at.%Si powders does not result in the formation of the Mo5Si3 crystalline phase, but the formation of a Mo(Si) supersaturated solid solution (SSS) and a completely amorphots phase after 5 h and 70 h milling, respectively. The free energy of the Mo-Sisystem has been calculated and it has been found that there is no driving force for the amorphization reaction under normal conditions. The amorphization by MA of the Mo-Si system is attributed to a solid-state amorphization reaction in which defects and a very fine grain size induced during milling process may raise the free energy of the crystalline intermetallic phase (for MoSi2) or the Mo(Si) supersaturated solid solution (for Mo5Si3) above that of the amorphous phase.