Pressurization effects in chromium

Abstract

Abstract Microstructural changes resulting from pressurization treatments have been studisd using transmission electron microscopy and an etch-pit technique; details of the etch-pit technique are given in an Appendix. ‘Free’ dislocations are produced at Cr2O3 particles in the chromium matrix due to the difference in compressibilities. Diffraction contrast analysis shows that the dislocation loops are prismatic and of vacancy type; their number is in reasonable agreement with strain calculations using compressibility data. The effect of pressurization on the tensile load/elongation curves for single crystals has been determined. The magnitude of the yield drop is decreased and the hardening rate for ‘single-slip’ orientations is increased, showing that the numerous pressure-induced dislocation sources lead to multiple slip from the onset of plastic flow. Etch-pit studies of the effects of various repeated pressurization and pressurization-ageing cycles correlate with changes in tensile characteristics.