Microstructure and hardness of W-25Re alloy processed by high-pressure torsion
(1. Department of Mechanical Engineering, Jiangnan University, Wuxi 214122, China;
2. Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology, Jiangnan University, Wuxi 214122, China;
3. Industrial and Manufacturing System Engineering Department, Iowa State University, Ames, Iowa 50011, United States;
4. School of Engineering, University of Liverpool, Brownlow Hill, Liverpool L69 3GH, United Kingdom)
Abstract: The evolution of microstructure and microhardness was studied in a commercial tungsten-25% rhenium (mass fraction) (W-25Re) alloy processed by the high pressure torsion (HPT) procedure under a pressure of 7.7 GPa up to 10 revolutions at different temperatures. The results show that the samples processed by 10 revolutions at room temperature could have the smallest grain size at around 0.209 μm. High saturation hardness (HV ~1200) could be achieved after the rapid strengthening stage for samples processed by 10 revolutions both at room temperature and at 573 K. Microstructural observation and analysis from Hall-Patch relationship could reveal that grain refinement and grain boundaries strengthening are the main factors of hardening mechanism in W-25Re alloy. It is also demonstrated that sintered W-25Re sample may have brittle phase separation phenomenon after HPT processing.
Key words: high-pressure torsion (HPT); W-25Re alloy; microstructure; Hall-Patch relationship; microhardness evolution