Impact and dynamic deformation behaviour of mechanically alloyed tungsten-based composites

Abstract

The tensile properties, impact energy and dynamic deformation behavior were investigated to examine the effects of microstructural factors on the mechanical properties of mechanically alloyed tungsten-based composites. The 93W-5.6Ni-1.4Fe composites were fabricated by mechanical alloying process using elemental powders of tungsten, nickel and iron, followed by sintering at temperature ranged from 1445 to 1485 degrees C under hydrogen atmosphere. Tungsten-based composite sintered using mechanically alloyed powders showed finer tungsten particles about 5-18 mu m with high density above 99% at shorter sintering time than fabricated by conventional liquid phase sintering process. When solid state sintered at 1445 degrees C, the microstructure showed that the solid solution matrix phase was isolated within interconnected tungsten particles. While, when liquid phase sintered above 1460 degrees C, the microstructure showed that the spherical tungsten particles were distributed within continuous solid solution matrix phase. The elongation and impact energy were increased, maintaining similar tensile strength, with increasing matrix volume fraction and decreasing the W/W contiguity as the sintering temperature increased. The dynamic torsional behavior using Kolsky bar exhibited the brittle fracture in solid state sintered composite, while showed the shear fracture liquid phase sintered composite.