Residual stress in spark-plasma-sintered and hot-pressed tantalum samples determined by X-ray diffraction methods

Tantalum samples have been compacted by the spark-plasma-sintering (SPS) sintering method. The sintering experiments have been conducted at temperatures between 1500 degrees C and 1900 degrees C and corresponding sintering times of 1 min each. The compacted samples of cylindrical shape have been characterized in respect of their residual stress by X-ray diffraction (sin(2)psi-method). The stress components in axial direction and in radial direction as occurring on the terminal circular faces of the samples have been determined. These results were compared with data obtained from conventional hot-pressed samples which were compacted between 1500 degrees C and 1700 degrees C for 60 min. In the lower temperature range below 1800 degrees C the stress parameters display no variation as a function of sintering method and sintering temperature. A dilatation parallel to the cylinder axis and a compression normal to the cylinder axis is observed. At 1900 degrees C significant changes are observed which coincides with structural and textural alterations in the samples. (C) 2007 Elsevier Ltd. All rights reserved.