Dense nanocrystalline W alloys: Enhancement of hardness and thermal stability by Al addition

Nanocrystalline W100-xAlx (x up to 20 at.%) powders obtained by mechanical alloying have been consolidated by spark plasma sintering (SPS). Alloying W with Al significantly improves the sinterability, allowing the fabrication of dense samples. The consolidation process keeps the nanocrystalline microstructure substantially unaffected, which contributes to the hardness of the final W-Al alloys. The room-temperature nano-and micro-hardness of dense W80Al20 alloy sintered at 1100 degrees C are as high as 18 and 14 GPa, respectively. These values are significantly higher than those previously reported for pure coarse-or submicron-grained W and may be ultimately ascribed to the grain boundary segregation of Al.