SOLID-STATE AMORPHIZATION TRANSFORMATIONS INDUCED BY MECHANICAL ALLOYING

The solid state amorphization transformations induced in the Fe-W, (Al or Ni)-(amorphous Fe-Si-B) and Ni-Ti systems were investigated by mechanical alloying. The structure and characteristics of the mechanically alloyed materials were studied by X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, differential thermal analysis, and magnetic measurement. Amorphization by mechanical alloying of the Fe-W system is attributed to a solid state amorphization reaction in which lattice distortion induced by supersaturation of tungsten in the iron crystal and a refinement of grain size may raise the free energy of the iron crystal supersaturated by tungsten above that of the amorphous phase. Amorphization by mechanical alloying of elemental aluminum or nickel metal and amorphous Fe-Si-B alloy can also be obtained within a composition range of the elemental metal. Different amorphization transformation paths are found in the Ni-Ti binary system mechanically alloyed in argon, nitrogen and oxygen atmospheres respectively.