Studies on Thermodynamic and Kinetic and Phase Evolution of W-Ni-Fe Powder during Mechanical Alloying

Abstract:

W6.56Ni2.28Fe tungsten heavy alloy from the elemental powders of W, Ni and Fe was mechanically alloyed(MA). Phase was defined by XRD. Microstructure was observed by TEM (JEM-2000 type). Phase evaluation, grain size and lattice distortion of these powders were determined and discussed. And nano-crystalline supersaturated solid solutions and amorphous were prepared by MA. A thermodynamic model was developed based on Miedema semi-experimental theory to calculate the driving force for phase evolution. The thermodynamic analysis showed that there is no chemical driving force to form amorphous alloys. The model of multilayer amorphization during MA was applied to illustrate the feasibility of amorphization of powder with neither ?Hmix << 0 nor DB >DA

Key words:mechanical alloying,amorphous,thermodynamic,multilayer amorphization,W-Ni-Fe