In this work,excess Cr_(2)O_(3)powders(by adding 25%,50%,and 75%Cr atoms relative to an equiatomic composition,respectively)are added to obtain equiatomic high entropy carbide ceramics with a single-phase rock salt st...In this work,excess Cr_(2)O_(3)powders(by adding 25%,50%,and 75%Cr atoms relative to an equiatomic composition,respectively)are added to obtain equiatomic high entropy carbide ceramics with a single-phase rock salt structure via the technology of carbothermal reduction and spark plasma sintering.The effects of excess Cr_(2)O_(3)addition on the solid solubility of Cr,elemental distribution,and mechanical properties of(Ta_(1)Ti_(1)V_(1)Cr_(x))C_(4)ceramics are investigated in detail.With the increase of excess Cr_(2)O_(3)addition,the Cr atom ratio of the synthesized powders increases from 7.0 at.%to 14.5 at.%,where Cr partially participates in the solid solution reaction to form(V,Cr)C solid solutions,while the remainder continues to exist in the form of Cr_(2)O_(3)powders.During spark plasma sintering,(V,Cr)C solid solutions dissolve into the(Ta,Ti)C solid solutions,resulting in a single-phase structured ceramics with dense and uniform element distribution.When the addition of excess Cr_(2)O_(3)is 25% and 50%,Cr atoms reach the equiatomic ratio in the as-sintered specimens.And the increase in Cr solid solubility is mainly attributed to the residual Cr_(2)O_(3)powders reacting with free carbon to form Cr_(3)C_(2),which then dissolves into(TaTiVCr)C ceramics during high-temperature sintering.Additionally,with the increase of Cr solid solubility,the nano-hardness of(TaTiVCr)C ceramics is improved,reaching up to 34.75 GPa with 50%excess Cr_(2)O_(3)addition,owing to the lattice distortion and solid solution strengthening caused by the relatively small atomic radius of Cr.展开更多
基金supported by the Key Program of Natural Science Foundation of Hunan Province(No.2024JJ3011)the National Natural Science Foundation of China(No.52271145)+2 种基金Natural Science Foundation of Hunan Province(No.2024JJ5075)the Open Research Fund of Songshan Lake Materials Laboratory(No.2023SLABFN27)Hunan Province’s Major Scientific and technological breakthroughs“Revealing the List and Taking Command”Project(No.2023ZJ1050)。
文摘In this work,excess Cr_(2)O_(3)powders(by adding 25%,50%,and 75%Cr atoms relative to an equiatomic composition,respectively)are added to obtain equiatomic high entropy carbide ceramics with a single-phase rock salt structure via the technology of carbothermal reduction and spark plasma sintering.The effects of excess Cr_(2)O_(3)addition on the solid solubility of Cr,elemental distribution,and mechanical properties of(Ta_(1)Ti_(1)V_(1)Cr_(x))C_(4)ceramics are investigated in detail.With the increase of excess Cr_(2)O_(3)addition,the Cr atom ratio of the synthesized powders increases from 7.0 at.%to 14.5 at.%,where Cr partially participates in the solid solution reaction to form(V,Cr)C solid solutions,while the remainder continues to exist in the form of Cr_(2)O_(3)powders.During spark plasma sintering,(V,Cr)C solid solutions dissolve into the(Ta,Ti)C solid solutions,resulting in a single-phase structured ceramics with dense and uniform element distribution.When the addition of excess Cr_(2)O_(3)is 25% and 50%,Cr atoms reach the equiatomic ratio in the as-sintered specimens.And the increase in Cr solid solubility is mainly attributed to the residual Cr_(2)O_(3)powders reacting with free carbon to form Cr_(3)C_(2),which then dissolves into(TaTiVCr)C ceramics during high-temperature sintering.Additionally,with the increase of Cr solid solubility,the nano-hardness of(TaTiVCr)C ceramics is improved,reaching up to 34.75 GPa with 50%excess Cr_(2)O_(3)addition,owing to the lattice distortion and solid solution strengthening caused by the relatively small atomic radius of Cr.
