Research On Microstructure And Properties Of Titanium Matrix Composites Prepared By In-situ Reaction Of SiC_P With New High Temperature Resistant Titanium Alloy

High temperature resistant titanium alloy and its composites have significant application background in aerospace engines and other fields.In this paper,argon protection sintering?APS?and spark plasma sintering?SPS?were used to prepare particle reinforced titanium matrix composites by in-situ reaction between SiC particles?SiC_p?and new high temperature resistant titanium alloy.The effects of SiC_p content?0vol.%,3.5vol.%,7vol.%,10vol.%?,solid solution and aging process,preparation process on the microstructure and properties of the materials were studied.The results are as follows:?1?The microstructure and properties of sintered composites prepared by APS process were studied.The results show that the addition of SiC_p has a certain refinement effect on the powder.The phase composition of the sintered composites are mainly?-Ti,TiC and Ti₅Si₃,and the grain size is refined step by step with the increase of SiC_p content.With the increase of SiC_p content,the apparent porosity and microhardness of the composite increase.The microhardness of 10vol.%SiC_p composite is 743.47HV,which is about 38.2%higher than that of the matrix?537.95HV?.?2?The effect of solid solution and aging process on the microstructure and properties of composites prepared by APS process were studied.The results show that the phase composition of the 10vol.%SiC_p composite after solid solution and aging treatment are still?-Ti,TiC and Ti₅Si₃.The solid solution and aging process do not change the phase composition of the composite.Under the solid solution aging process of HT5?1000°C/3h/AC+750°C/3h/AC?,the enhanced phase content is the highest and the strengthening effect is the best.With the solution temperature increases,the grain size of the composite increases gradually.The best solid solution and aging process is 1000°C/3 h/AC+750°C/3h/AC,the microhardness is 1062.08 HV under this state,which is about 42.9%higher than sintered state?743.47 HV?.?3?The high temperature oxidation resistance of composites after solid solution and aging treatment prepared by APS process was studied.The results show that the oxidation products of the composites oxidized at 750°C and 850°C for 100h are similar and they are mainly composed of TiO₂,Al₂O₃ and SiO₂.At 750°C,the average oxidation rate k⁺value of the composites are less than 1g·m^-2·h^-1,which reaches the oxidation resistance level.With the oxidation temperature increases,the oxidation resistance declines.Under the same oxidation temperature,as the SiC_p content increases,the oxide film thickness and the oxidation weight gain decrease gradually.The oxidation weight gain of the composite with 10vol.%SiC_p oxidized at 750°C and850°C is 3.4194 mg·cm^-22 and 12.0129 mg·cm^-2,respectively,which is only 31.23%and 72.61%of the matrix alloy,indicating that SiC_p can significantly improve the material's high temperature oxidation resistance.?4?The hot corrosion resistance of composites after solid solution and aging treatment prepared by APS process was studied.The results show that as the temperature increases,the corrosion resistance of the material decreases and the corrosion weight gain of the materials decreases with the increase of SiC_p content.The corrosion weight gain of the 10vol.%SiC_p composite under 750°C and 850°C is6.1575 mg·cm^-22 and 30.5706 mg·cm^-2,respectively,which is only 39.94%and64.51%of the matrix alloy.The corrosion products of the materials are similar under two temperatures,and are mainly composed of TiO₂,Al₂O₃,SiO₂,NaTiO₂,Na₂Si₂O₅,TiS₂,etc.In addition,the thickness of the corrosion layer decreases gradually with the increase of SiC_p content,and the corrosion resistance is improved.?5?The microstructure and properties of the composites prepared by SPS process were studied.The results show that the phase composition of the composites prepared by SPS process is the same as that of the APS process,and there is no significant difference.The apparent porosity of the matrix and 7vol.%SiC_p composite is only1.26%and 1.57%,respectively,which is significantly lower than that of the APS process.The microhardness of the matrix and 7vol.%SiC_p composite is 532.25HV and 724.56HV,respectively,which is not much different from the microhardness of materials prepared by APS process.The materials prepared by the SPS process have excellent oxidation resistance at 750°C,and all reach the oxidation resistance level,and 7vol.%SiC_p composite reaches the complete oxidation resistance level.The oxidation weight gain of the matrix and 7vol.%SiC_p composites is only 23.5%and26.2%of the materials prepared by APS process,and the oxidation resistance is significantly improved.In summary,this paper creatively used APS and SPS processes to prepare TiC and Ti₅Si₃ particle-reinforced titanium matrix composites by in-situ reaction between SiC_p and new high temperature resistant titanium alloy,which provides a reference for the design and preparation of titanium matrix composites.