Abstract
Neck-seeds among pure titanium powders were homogeneously caused by the pulse discharge as an early stage in spark sintering. Their compacts showed some characteristic microstructures by the adjustment of process parameters such as temperature-history, -amplitude and applied pressure in the following continuous current discharge. Such property-controls might be carried out on the basis of the micro phenomena caused in or between powders. The allotropic transformation of α and β phases was utilized for achievement of full density and microstructure control, as case study of property-controls on Ti compacts. Both nearly full density and characteristic microstructures were achieved by the control of heat and cool cycles in temperature-ranges below and above β transus, due to excellent thermal and load control-ability in the spark sintering equipment. The 0.2% proof and tensile strength were increased, only by rising of relative densities. In contrast, the tensile elongation and reduction of area were affected by both relative densities and microstructures. The relation among mechanical properties, density and microstructures was investigated on obtained compacts, and one method for their property-controls was proposed on the basis of this result.
