Study On Preparation And Mechanical Properties Of Ceramic Particles Reinforced NbTi-matrix Composites

In this paper,ZrB2 particles reinforced NbTi-matrix composites xZrB2-(Nb-20wt.%Ti)was prepared by vacuum hot pressing sintering at 1600?.30MPa and argon gas(referred to as xZrB2-NbTi,x=0,15wt.%,30wt.%.45wt.%,60wt.%).X-ray powder diffractometry(XRD),Scanning electron microscopy(SEM)andEnergy dispersive spectroscopy(EDS)were used to analyze the phase and microstru-cture of the composites;The density was obtained by Archimedes principle;The microhardness value was measured by the hardness tester;The room temperature elastic modulus was measured by room temperature resonance method;The fracture toughness at room temperature and high temperature(800-1300?)was detected by the single-edge notched beam method;The compression test at room temperature and high temperature(800-1300?)was carried out using a mechanical testing machine.The Nb-20wt.%Ti alloy consists of a NbTi solid solution(Nb,Ti)ss and ?-Ti phase.The xZrB2-NbTi(x=15-60wt.%)compositesare based on a Nb-based solid solution Nbss generating(Nb,Ti)B and ZrO phase.The maximum reaction concentration of ZrB2in Nb-20wt.%Ti alloy is 30-45wt.%.The room temperature fracture toughness of xZrB2-NbTi composites is between 6.95-13.04MPa·m1/2,the room temperature elastic modulus is between 111.12-343.96GPa,the density is greater than 96%,and the microhardness is between 381.1-1701.7HV.The Nb-20wt.%Ti alloy was plastically fractured under the room temperature compres-sion test,and the brittle fracture occurred in the xZrB2-NbTi(x=15-60wt.%)compo-sites under the room temperature compression test,(Nb,Ti)B second phase strengthening,ZrO dispersion strengthening and solid solution strengthening of Zr solid solution in Nbss improve the strength of the composites.Displacement of solid solution(Nb,Ti)ss is beneficial to the room temperature fracture toughness of the composites.The compression peak stress of the xZrB2-NbTi(x=15-60wt.%)composites at 800? is between 1011-1613MPa.When ZrB2 increases,the peak stress of xZrB2-NbTi composites increases first and then decreases,and 45wt.%ZrB2 is added to obtain the maximum stress value,because a large number of hard phases(Nb,Ti)B provide high temperature strength,ZrB2 particles are distributed in Nbss,and there is no obvious crack at the phase interface.As the test temperature increases,the peak stress value of the composites decreases and occursbrittle-ductile transition.The brittle-ductile transition temperature of the xZrB2-NbTi composites(x=15-60wt.%)is between 900-1300?.As the ZrB2 increases,the peak strain of the xZrB2-NbTi composites decreases and the high temperature fracture toughness decreases.The fracture toughness of the xZrB2-NbTi(x=15-60wt.%)composites at 800-1300? is between 1.97-12.03MPa-m1/2.