Impact and dynamic deformation behavior of mechanically alloyed tungsten heavy alloy

Abstract

93W-5.6Ni-1.4Fe tungsten heavy alloy was fabricated by mechanical alloying process using elemental powders of tungsten, nickel and iron, followed by sintering at temperatures of 1445 similar to 1485 degrees C under hydrogen atmosphere. The tungsten heavy alloy sintered using mechanically alloyed powders showed finer tungsten par tides about 5 similar to 18 mu m with high density above 99% at shorter sintering time than that fabricated by conventional liquid-phase sintering process. Charpy impact energy of mechanically alloyed tungsten heavy alloy increased with increasing the matrix volume fraction and with decreasing the W/W contiguity. The high strain rate dynamic deformation behavior of tungsten heavy alloys using torsional Kolsky bar test exhibited different fracture modes dependent on microstructure. While the brittle intergranular fracture mode was dominant when the tungsten particles were contiguously interconnected in tungsten heavy alloys solid-state sintered below 1460 degrees C, the ductile shear fracture mode was dominant when the tungsten particles were surrounded by ductile matrix phase in tungsten heavy alloys liquid-phase sintered above 1460 degrees C.