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 (similar to2.0 GPa) similar to that of an as-cast bulk amorphous Ni59Zr20Ti16Si2Sn3 alloy (similar to2.2 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. (C) 2003 Elsevier Science B.V. All rights reserved.