Sintering of β Titanium: Role of Dislocation Pipe Diffusion

Abstract

Sintering of titanium in its high temperature β phase was studied by isothermal dilatometry. The sintering shrinkage y did not follow the normal time exponent type of behaviour, instead being described by the equation y = Kt^m/[1− (A + Bt)²], where m = 1·93±0·07, with an activation energy of 62−90 kJ mol⁻¹. A detailed analysis of these results, based on the ‘anomalous’ diffusion behaviour reported for β titanium, is carried out. It is shown that the generation of a high density of dislocations during the α→β phase transformation, coupled with sluggish recovery at the sintering necks, enables sintering mass transport by pipe diffusion through dislocation cores from sources of matter within the particles to become dominant. PM/0708