Thermal stability of bimodal grain structure in a cobalt-based superalloy subjected to high-temperature exposure
来源期刊：Rare Metals2021年第4期
论文作者：Cheng-Lin Li Jeong Mok Oh Seong-Woo Choi Xin-Ming Mei Jae-Keun Hong Jong-Taek Yeom Qing-Song Mei Zhen-Tao Yu Chan Hee Park
文章页码：877 - 884
摘 要：The present work investigates the thermal stability and mechanical properties of a Co-20 Cr-15 W-10 Ni（wt%） alloy with a bimodal grain（BG） structure.The BG structure consisting of fine grains（FGs） and coarse grains（CGs） is thermally stable under high-temperature exposure treatments of 760℃ for 100 h and 870℃ for 100-1000 h.The size of both FGs and CGs remains no significant changes after thermal exposure treatments.The microstructural stability is associated with the slow kinetics of grain growth and the pinning of carbides.The thermal stability enables to maintain the BG structures,leading to the same mechanical properties as the sample without thermal exposure treatment.In particular,the BG alloy samples after thermal exposure treatment exhibit superior mechanical properties of both high strength and high ductility compared to the unimodal grain（UG） structured ones.The BG structure of the alloy samples after thermal exposure is capable of avoiding severe loss of ductility and retaining high strength.More specifically,the ductility of the BG alloy samples after thermal exposure treatments of 870℃ for 500-1000 h is ten times higher（44.6% vs.3.5% and 52.6% vs.5.0%） than that of the UG ones.The finding in the present work may give new insights into high-temperature applications of the Co-20 Cr-15 W-10 Ni alloy and other metallic materials with a BG structure.
Cheng-Lin Li1，Jeong Mok Oh2，Seong-Woo Choi2，Xin-Ming Mei1，Jae-Keun Hong2，Jong-Taek Yeom2，Qing-Song Mei1，Zhen-Tao Yu3，Chan Hee Park2
1. School of Power and Mechanical Engineering,Wuhan University2. Advanced Metals Division,Korea Institute of Materials Science3. Institute of Advanced Wear and Corrosion Resistant and Functional Materials,Jinan University
摘 要：The present work investigates the thermal stability and mechanical properties of a Co-20 Cr-15 W-10 Ni（wt%） alloy with a bimodal grain（BG） structure.The BG structure consisting of fine grains（FGs） and coarse grains（CGs） is thermally stable under high-temperature exposure treatments of 760℃ for 100 h and 870℃ for 100-1000 h.The size of both FGs and CGs remains no significant changes after thermal exposure treatments.The microstructural stability is associated with the slow kinetics of grain growth and the pinning of carbides.The thermal stability enables to maintain the BG structures,leading to the same mechanical properties as the sample without thermal exposure treatment.In particular,the BG alloy samples after thermal exposure treatment exhibit superior mechanical properties of both high strength and high ductility compared to the unimodal grain（UG） structured ones.The BG structure of the alloy samples after thermal exposure is capable of avoiding severe loss of ductility and retaining high strength.More specifically,the ductility of the BG alloy samples after thermal exposure treatments of 870℃ for 500-1000 h is ten times higher（44.6% vs.3.5% and 52.6% vs.5.0%） than that of the UG ones.The finding in the present work may give new insights into high-temperature applications of the Co-20 Cr-15 W-10 Ni alloy and other metallic materials with a BG structure.
关键词：
