Y-modified Cr-Al coatings were co-deposited on DZ125 alloy by a pack cementation process,and the microstructures,constituent phases,and formation mechanisms of the obtained coatings were studied.The oxidation resistan...Y-modified Cr-Al coatings were co-deposited on DZ125 alloy by a pack cementation process,and the microstructures,constituent phases,and formation mechanisms of the obtained coatings were studied.The oxidation resistance of the coatings was also investigated.The experimental results show that the coating prepared by co-depositing Cr-Al-Y at 1050℃for 2 h has a multi-layered structure with an outer layer composed of Cr and Ni_(3)Cr_(2),a middle layer composed of Ni_(3)Cr_(2) and Al_(13)Co_(4),and an inner layer composed of Ni_(3)Al.The co-deposited Y is mainly present in the outer and middle layers of the coating.The coating formation process follows a sequential deposition mechanism in which Al is deposited during the initial stage,followed by Cr deposition.After oxidation at 1100℃for 100 h,a dense Cr_(2)O_(3)·Al_(2)O_(3) scale forms on the obtained coating,which effectively protects the DZ125 alloy from oxidation by preventing the inward diffusion of oxygen.展开更多
In this study, Y-and Ce-modified Cr coatings applied by pack cementation method were prepared on the surface of open-cell nickel-based alloy foam. The morphologies and microstructures of Y- and Ce-modified Cr coatings...In this study, Y-and Ce-modified Cr coatings applied by pack cementation method were prepared on the surface of open-cell nickel-based alloy foam. The morphologies and microstructures of Y- and Ce-modified Cr coatings with various Y and Ce contents were investigated in detail. Then, the effects of Y and Ce addition on the mechanical properties of open-cell nickel-based alloy foams were analyzed and compared. Simultaneously, the energy absorption capacity and energy absorption efficiency of the Y- and Ce-modified Cr coated alloy foams were discussed and compared at the room and high temperatures. The results show that Cr coatings containing minor amounts of rare earth element (Y and Ce) are well adhered to the nickel-based foam struts. Especially, the microstructure of the 2 wt% Ce-modified Cr coating is denser and uniform. In addition, the compressive strength and plateau stress of Y- and Ce-modified Cr coated alloy foams firstly increase and then decrease by increasing the Y and Ce contents at room and high temperatures. The energy absorption capacity of Y/Cr and Ce/Cr coated alloy foams increases linearly with the strains increasing. The Ce/Cr coated alloy foams can absorb more energy than Y/Cr coated alloy foams in the plateau and densification regions at room temperature. Compared to those at room temperature, the Y- and Ce-modified Cr coated alloy foams show higher energy absorption efficiency when deforma- tion within 10%-30% at high temperature.展开更多
基金Funded by the Basic Scientific Research of the North Minzu University(FWNX42)the Natural Science Foundation of Ningxia(2020AAC02025)+1 种基金the National Natural Science Foundation of China(51961003 and 52161009)the Ningxia Youth Talents Supporting Program(TJGC2019040)。
文摘Y-modified Cr-Al coatings were co-deposited on DZ125 alloy by a pack cementation process,and the microstructures,constituent phases,and formation mechanisms of the obtained coatings were studied.The oxidation resistance of the coatings was also investigated.The experimental results show that the coating prepared by co-depositing Cr-Al-Y at 1050℃for 2 h has a multi-layered structure with an outer layer composed of Cr and Ni_(3)Cr_(2),a middle layer composed of Ni_(3)Cr_(2) and Al_(13)Co_(4),and an inner layer composed of Ni_(3)Al.The co-deposited Y is mainly present in the outer and middle layers of the coating.The coating formation process follows a sequential deposition mechanism in which Al is deposited during the initial stage,followed by Cr deposition.After oxidation at 1100℃for 100 h,a dense Cr_(2)O_(3)·Al_(2)O_(3) scale forms on the obtained coating,which effectively protects the DZ125 alloy from oxidation by preventing the inward diffusion of oxygen.
基金financially supported by the National Natural Science Foundation of China (Nos.51501133 and 51405358)the China Automobile Industry Innovation and Development Joint Fund (No.U1564202)+1 种基金the Natural Science Foundation of Hubei Province (No.2016CFC773)the State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology (No.AWJ-M16-11)
文摘In this study, Y-and Ce-modified Cr coatings applied by pack cementation method were prepared on the surface of open-cell nickel-based alloy foam. The morphologies and microstructures of Y- and Ce-modified Cr coatings with various Y and Ce contents were investigated in detail. Then, the effects of Y and Ce addition on the mechanical properties of open-cell nickel-based alloy foams were analyzed and compared. Simultaneously, the energy absorption capacity and energy absorption efficiency of the Y- and Ce-modified Cr coated alloy foams were discussed and compared at the room and high temperatures. The results show that Cr coatings containing minor amounts of rare earth element (Y and Ce) are well adhered to the nickel-based foam struts. Especially, the microstructure of the 2 wt% Ce-modified Cr coating is denser and uniform. In addition, the compressive strength and plateau stress of Y- and Ce-modified Cr coated alloy foams firstly increase and then decrease by increasing the Y and Ce contents at room and high temperatures. The energy absorption capacity of Y/Cr and Ce/Cr coated alloy foams increases linearly with the strains increasing. The Ce/Cr coated alloy foams can absorb more energy than Y/Cr coated alloy foams in the plateau and densification regions at room temperature. Compared to those at room temperature, the Y- and Ce-modified Cr coated alloy foams show higher energy absorption efficiency when deforma- tion within 10%-30% at high temperature.