The Co-Cr-W ternary system was critically assessed using the CALPHAD technique.The solution phases including the liquid,γ-Co,ε-Co and α-Cr were described by a substitutional solution model.The σ,μ and R phases we...The Co-Cr-W ternary system was critically assessed using the CALPHAD technique.The solution phases including the liquid,γ-Co,ε-Co and α-Cr were described by a substitutional solution model.The σ,μ and R phases were described by three-sublattice models of（Co,W）8（Cr,W）4（Co,Cr,W）18,（Co,Cr,W）7W2（Co,Cr,W）4 and（Co,W）27（Cr,W）14（Co,Cr,W）12,respectively,in order to reproduce their homogeneity ranges.A self-consistent set of thermodynamic parameters for each phase was derived.The calculated isothermal sections at 1 000,1 200 and 1 350 ℃ are in good agreement with the experimental data.A eutectoid reaction of R μ＋γ-Co＋σ in this ternary system was predicted to occur at 1 022 ℃.展开更多
The viscoplastic friction and nanostructure formation mechanism of laser-clad Co-based coating were studied by rotary friction between laser-clad Co-Cr-Ni-Mo coating and WC-Co rod.The friction coefficient,friction int...The viscoplastic friction and nanostructure formation mechanism of laser-clad Co-based coating were studied by rotary friction between laser-clad Co-Cr-Ni-Mo coating and WC-Co rod.The friction coefficient,friction interface temperature and axial displacement—time curves during rotary friction process were measured.The results showed that all the curves firstly experienced rising stage and then steady stage.The rising stage corresponded to sliding friction while the steady stage corresponded to viscoplastic friction.After viscoplastic friction processing,three typical zones of viscoplastic deformation zone,thermo-mechanically affected zone,and original laser-clad zone can be observed successively from the friction surface to the interior.The viscoplastic deformation significantly crushed the network M23C7 phase in original laser-clad zone and made it dispersively distributed with equiaxial shape and in nano-scale.The viscoplastic zone,in width of 37-131 μm,is mainly characterized by refined M23C7 and α-Co phase with grain size bellow 50 nm,and even a small quantity of amorphous.Thus,the hardness of viscoplastic zone about HV997 was improved compared with the hardness of original laser-clad zone about HV600.展开更多
基金Project(50771027)supported by the National Basic Research Program of ChinaProject(50771027)supported by the National Natural Science Foundation of China
文摘The Co-Cr-W ternary system was critically assessed using the CALPHAD technique.The solution phases including the liquid,γ-Co,ε-Co and α-Cr were described by a substitutional solution model.The σ,μ and R phases were described by three-sublattice models of（Co,W）8（Cr,W）4（Co,Cr,W）18,（Co,Cr,W）7W2（Co,Cr,W）4 and（Co,W）27（Cr,W）14（Co,Cr,W）12,respectively,in order to reproduce their homogeneity ranges.A self-consistent set of thermodynamic parameters for each phase was derived.The calculated isothermal sections at 1 000,1 200 and 1 350 ℃ are in good agreement with the experimental data.A eutectoid reaction of R μ＋γ-Co＋σ in this ternary system was predicted to occur at 1 022 ℃.
基金Project(51101126) supported by the National Natural Science Foundation of ChinaProjects(20110491684,2012T50817) supported by the China Postdoctoral Science FoundationProject(20110942K) supported by the Open Fund of State Key Laboratory of Powder Metallurgy,China
文摘The viscoplastic friction and nanostructure formation mechanism of laser-clad Co-based coating were studied by rotary friction between laser-clad Co-Cr-Ni-Mo coating and WC-Co rod.The friction coefficient,friction interface temperature and axial displacement—time curves during rotary friction process were measured.The results showed that all the curves firstly experienced rising stage and then steady stage.The rising stage corresponded to sliding friction while the steady stage corresponded to viscoplastic friction.After viscoplastic friction processing,three typical zones of viscoplastic deformation zone,thermo-mechanically affected zone,and original laser-clad zone can be observed successively from the friction surface to the interior.The viscoplastic deformation significantly crushed the network M23C7 phase in original laser-clad zone and made it dispersively distributed with equiaxial shape and in nano-scale.The viscoplastic zone,in width of 37-131 μm,is mainly characterized by refined M23C7 and α-Co phase with grain size bellow 50 nm,and even a small quantity of amorphous.Thus,the hardness of viscoplastic zone about HV997 was improved compared with the hardness of original laser-clad zone about HV600.
