The Study Of Composition Design And Performance Of Zr_xNb_1-xC And ZrC_xN_1-x Alloys

Zr and Zr alloys have been widely used in nuclear industry and chemical industry dueto their unique properties, such as good corrosion resistance, excellent anti-neutronirradiation, good high-temperature resistance and low density. Future studies are ofconsiderable scientific and technological significance to broaden the applications andpromote better use of Zr alloys.It has been an importance direction in materials science to design novel materials onatomic and molecular level. The first principles calculations have been performed in thispaper to design the optimal composition of Zr_xNb_1-xCand ZrC_xN_1-xsystems and predicttheir properties, through which the physical relationship between mechanical propertiesand valence electron concentration is explored and new zirconium alloy with goodmechanical properties is designed.The structural parameters, mechanical properties and electronic structures ofZr_xNb_1-xCand ZrC_xN_1-xas a function of composition were studied systematically based onthe disordered solid solution model via virtual crystal approximation method. Thecalculated results show that the lattice parameter a of Zr_xNb_1-xCand ZrC_xN_1-xincreaseswith the increasing x. The elastic constants of Zr_xNb_1-xCand ZrC_xN_1-xwere calculated. Itcan be found that their properties change with the variation of x. Zr_0.21Nb_0.79C may possessthe highest hardness among the Zr_xNb_1-xCalloys because it has the highest shear modulus215GPa and the higher bulk modulus294GPa. According to the hardness formula,ZrC_0.7N_0.3possesses the highest hardness28.4GPa. The electronic structures andthermodynamic properties of Zr_0.21Nb_0.79C and ZrC_0.7N_0.3were calculated. It was foundthat these two alloys are metallic and stable thermodynamically. Through the systematicalresearch, it can be found that regulation and control of the crystal valence electronconcentration is an effective method to design new materials.