Effect Of Alloying On Microstructure,Magnetic And Mechanical Properties Of TiC–WC–Ni Cermets

The effect of 3–12 wt.%TiN addition on microstructure,magnetic and mechanical properties of TiC–10WC–25Ni cermet were investigated and the effect of 3–15 wt.%Mo addition on microstructure and magnetic,mechanical properties of TiC–12TiN–10WC–25Ni cermet have also been studied in the present work,and then,the influence of alloying components TiN,Mo content on magnetic transition of Ni-binder phase of TiC–10WC–25Ni cermet have been discussed.The microstructures of TiC–xTiN–10WC–25Ni(x=0,3,6,9,12 wt.%)cermet and TiC–12TiN–10WC–xMo–25Ni(x=0,3,6,9,12,15 wt.%)cermets consisted of disperse TiC or Ti(C,N)ceramic grains and Ni-based binder phase after sintering in vacuum at 1430oC for 1 h,Obviously.Ceramic grains generally consisted of black core,white inner rim and grey outer rim.The volume fraction of black core decreased and ceramic grains became fine in size with increasing TiN content.Ceramic grains became fine when the TiN content above 3wt.%.The volume fraction of black core decreased and ceramic grains became fine with increasing Mo content.TiC–xTiN–10WC–25Ni(x=0,3,6,9,12 wt.%)cermets showed weak magnetic hysteresis at room temperature,regardless of TiN content,howevr RT M_s and M_r decreased with increasing TiN content.When TiN content was 12 wt.%,cemerts became paramagnetic at room temperature,whose Curie temperature was about 257 K,which was mainly attributed to that Ti,W content in Ni binder phase increased with increasing TiN content.Transverse rupture strength of TiC–xTiN–10WC–25Ni(x=0,3,6,9,12 wt.%)cermets increased with increasing TiN content,TRS reached to 1859 MPa when TiN content at 12wt.%,which might be attributed to several factors,especially,ceramic grain refinement,moderate thickness of grey outer rim in ceramic grains,and solid solution strengthening of binder phase.Hardness did not significantly vary with TiN content,which was mainly attributed to the synergistic effect of the following factors:solid solution strengthening of binder phase,ceramic grain refinement,and the volume fraction decrease of black core in ceramic grains.TiC–12TiN–10WC–xMo–25Ni(x=0,3,6,9,12,15 wt.%)cermets showed paramagnetic at room temperature,regardless of Mo content,however,RT M and M_r decreased with increasing Mo content.When Mo content was 15 wt.%,whose Curie temperature was about 30 K,which was mainly attributed to that Ti,Mo,W content in Ni binder phase increased with increasing Mo content.weakening magnetic exchange interaction between Ni atoms.Transverse rupture strength of TiC–12TiN–10WC–xMo–25Ni(x=0,3,6,9,12,15 wt.%)cermets increased with increasing Mo content,TRS reached to peak value when Mo content at 6 wt.%,which might be attributed to ceramic grain refinement,solid solution strengthening of binder phase and high strength of interace between ceramic grains and binder phase.Hardness increased then decreased sightly with increasing Mo content,which was mainly attributed to the following factors:the volume fraction decrease of black core in ceramic grains,solid solution strengthening of binder phase,and ceramic grain refinement.