Enhancing Cr solubility via adding excess Cr₂O₃to fabricate equiatomic(TaTiVCr)C ceramics AITranslate

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Chinese Library Classification Number:TQ174.1[化学工程—陶瓷工业]

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In this work,excess Cr₂O₃powders(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 Cr₂O₃addition on the solid solubility of Cr,elemental distribution,and mechanical properties of(Ta₁Ti₁V₁Cr_x)C₄ceramics are investigated in detail.With the increase of excess Cr₂O₃addition,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 Cr₂O₃powders.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 Cr₂O₃is 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 Cr₂O₃powders reacting with free carbon to form Cr₃C₂,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 Cr₂O₃addition,owing to the lattice distortion and solid solution strengthening caused by the relatively small atomic radius of Cr.