The sintering rate in the final stage during HIP has been investigated by measurement of relative density of compacts which were preliminary sintered in vacuum. The activation energy of the final stage HIP-sintering rate
Qh of 218 kJ/mol and the stress exponent
nh of 4.5 are obtained for the pure titanium compact with an equiaxed structure and
Qh of 213 kJ/mol and
nh of 4.7 are obtained for that with a non-equiaxed structure. These values are approximately equal to the creep parameters,
Qc and
nc, obtained from creep experiments. The sintering rate of the pure titanium with the equiaxed structure is larger than that with the non-equiaxed structure under the same condition of temperature and pressure in the HIP process, which is influenced by the structure of compacts pre-sintered in vacuum. This is mainly due to the variation of
A value in the equation of power-law creep influenced by the microstructure. The control of presintered structure is important for the followed HIP process.
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