Sintering of a nano-crystalline tungsten heavy alloy powder

Abstract

Abstract<br><br>A nano-crystalline Tungsten heavy alloy powder was obtained by mechanical<br><br>alloying of elemental powders in a jar mill with a high ball to powder ratio. The chemical<br><br>composition of the primary powder was 93W-4.9Ni-2.1Fe -wt. %-. The mechanically<br><br>alloyed powder had 22 nm sized tungsten crystallites distributed in an amorphous nickel<br><br>base phase. Mechanical alloying reduced particle size of powders and also yielded to<br><br>more uniform particles size distribution. Sintering behavior and microstructural<br><br>development of that powder were studied and compared with a conventionally mixed<br><br>powder. Mechanically stored energy and better distribution of primary elements in Nanocrystalline powder had decreased motivation energy of sintering and that powders<br><br>showed more densification at relatively lower sintering temperatures. Sintering at low<br><br>temperatures can depress grain growth during sintering and provide desirable properties.<br><br>A transient intermetallic phase was formed in the nano-crystalline powder during<br><br>sintering that has not been seen in conventionally mixed powders.