Abstract

The high temperature deformation behavior of the activated sintered W powder compacts was investigated. The W compact showed the relative density of 94% with the average W grain size of 23mutextrmm by activated sintering at 1400°C for 1 hour. Compression tests were carried out in the temperature range of 900-1100°C at the strain rate range of 100/sec - 10-3/sec. True stress-strain curve and microstructure exhibited the grain boundary brittleness which was dependent on the compression test temperature. The activated sintered W compact showed that the maximum stress as well as the strain at the maximum stress was abruptly decreased as the test temperature increase from 900°C to 1000 and 1100°C regardless of the strain rate. The discrepancy of the microstructure in the specimen center was obviously observed with the increase of the test temperature. After compression test at 900°C the W grain was severely deformed normally against the compression axis. However, after compression test at 1000°C and 1100°C the W grain was not deformed, but the microcrack was formed in the W grain boundary. The Ni-rich second phase segregated along the W grain boundary could be partly unstable over 900°C and affect the poor mechanical property of the activated sintered W compact.

• Keywords: Activated sintering;W-Ni;Compressive test;High temperature deformation;