Dilatometry of attrition milled nanocrystalline titanium powders

Abstract

The sintering behavior of nanosized titanium powders was investigated by ditatometry. The nanosized Ti powders (40 nm) were produced by the attrition milling of micron sized Ti powders (12 mu m) in Ar atmosphere. Sintering was carried out in Ar atmosphere in the temperature range of 450-1250 degrees C for nanosized Ti and 650-1250 degrees C for micron sized Ti by heating at 10 degrees C/min, up to the sintering temperature followed by isothermal holding for I It. The nanosized Ti powders exhibited a lower sintering onset temperature, larger shrinkage, larger shrinkage rate, and lower activation energy for sintering as compared to the micron sized Ti powders. The sintered micron sized Ti specimens exhibited both intraagglomerate and interagglomerate porosity while the nanosized Ti specimens exhibited well densified agglomerates (almost no interagglomerate porosity) and large intraagglomerate porosity. In nanosized Ti grain growth was found to take place beyond 700 degrees C and reached a maximum of 66 nm in samples sintered at 1100 degrees C. (c) 2006