Synthesis of Ni-based bulk amorphous alloys by warm extrusion of amorphous powders

A high strength Ni-based bulk amorphous alloy is synthesized by warm extrusion of gas atomized amorphous powder. The Ni59Zr20Ti16Si2Sn3 amorphous powder obtained by a high pressure Ar gas atomization method has a wide super-cooled liquid region of 63 K. Warm extrusion of the amorphous powders in the super-cooled liquid state successfully yielded a fully consolidated bulk amorphous Ni59Zr20Ti16Si2Sn3 alloy. The processing conditions for extrusion are obtained from the time–temperature-transformation curve for the onset of crystallization of the amorphous powder. Lower extrusion ratio of 5 is preferred for the retention of the single amorphous phase during extrusion at 848 K. The extruded bulk amorphous Ni59Zr20Ti16Si2Sn3 alloy exhibits a high strength level (∼2.0 GPa) similar to that of an as-cast bulk amorphous Ni59Zr20Ti16Si2Sn3 alloy (∼2.2 GPa). The mechanical behavior of the extruded alloy under the compressive condition shows no anisotropy in the longitudinal and transverse directions to the extrusion direction.