METASTABLE BCC AND AMORPHOUS NI PRODUCED BY MECHANICAL ALLOYING AND CHEMICAL LEACHING

B.c.c. and amorphous Ni are obtained by a technique combining mechanical alloying of Ni and Al elemental powders, and chemical leaching of Al in basic solution. The as-milled and milled-and-leached specimens are characterized by X-ray diffraction, transmission electron microscopy, high pressure differential thermal analysis, differential scanning calorimetry and magnetization measurements. B.c.c. and amorphous Ni phases exhibit paramagnetic characters at low temperatures and transform to the ferromagnetic f.c.c. Ni phase at high temperatures. Low temperature, specific heat measurements indicate the enhancement of its electronic coefficient in the paramagnetic b.c.c. and amorphous Ni in comparison with that of annealed f.c.c. Ni.