首页|Hierarchical nanostructure stabilizing high content coherent nanoprecipitates in Al-Cr-Fe-Ni-V high-entropy alloy
Hierarchical nanostructure stabilizing high content coherent nanoprecipitates in Al-Cr-Fe-Ni-V high-entropy alloy
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High-density coherent nanoprecipitates have been widely introduced into the design of new structural materials to achieve a superior strength-ductility balance.However,the thermal instability of nanostruc-tures limits their fabrication and application.In this study,we investigated the temporal evolution of nanoprecipitates in coherent nanoprecipitation-strengthened Al0.5Cr0.9FeNi2.5V0.2 high-entropy alloy dur-ing isothermal aging.When annealed at 600 ℃ for more than 100 h,we found that its nanoprecipitates were invariably stable,with no obvious changes occurring in terms of morphology and distribution.The excellent stability was mainly attributed to the restricted state of interface migration and diffusion ow-ing to the hierarchical nanostructure.The Cr-enriched nano-lamellar BCC phase divided the Cr-depleted FCC(L12)matrix,forming barriers to long-range diffusion and resulting in a kinetically slow coarsening rate.As the nano-lamellar BCC phase spheroidized as the aging temperature increased to 700 ℃,the diffusion barriers were destroyed.Remarkable coarsening occurred after that,which further verified the significant effect of the nano-lamellar BCC phase on the microstructural stability.These results provide a paradigm for designing alloys stabilized via hierarchical nanostructure,achieving good strength-ductility synergy while excellent thermal stability.
School of Materials Science and Engineering,Beijing Institute of Technology,Beijing,100081,China
Key Laboratory of Marine Materials and Related Technologies,Zhejiang Key Laboratory of Marine Materials and Protective Technologies,Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences,Ningbo,315201,China
Department of Physics,City University of Hong Kong,Kowloon,Hong Kong,China
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