Study On The Volatilization Mechanism Of TC4 Components And The Ingredients Parameters

TC4 alloy is widely used in aerospace because it has a series of advantages,such as high strength,high toughness,good plasticity,resistance to high temperatures and resistance to corrosion.It is the most widely used and the largest yield titanium alloy at present.As the melting point of the alloy component A1 and the matrix Ti is different,the Al will volatilize in the melting process,which causes the control of the alloy composition to be difficult.When the alloy is batching,A1 is added to supplement the amount of volatilization loss.Therefore,it is predicted that the volatilization loss of the alloying element A1 and the prediction of alloying ingredients are significant.In this paper,by calculating the infinite dilution activity coefficients of Ti-Al,Ti-V and Al-V,the reliability is verified and an accurate and reliable binary activity is calculated.The results show that the infinite dilution activity coefficients of Ti-Al binary alloy are 0.0023 and 0.002,respectively.When 2050K,the infinite dilution activity coefficients of Ti-V binary alloy are 1.435 and 2.0017,respectively.When 1273K is 1273K,the infinite dilution activity coefficients of Al-V binary alloy are 1.194 and 3.387,respectively.The infinite dilutees coefficient of three binary alloys were calculated,the MIVM model and the Wilson equation of the three element alloy were used to calculate the activity coefficient of TC4 alloy.Predicted experimental values for comparison.The results show that the MIVM model is more suitable for the prediction of TC4 ternary alloy system activity coefficient.Ternary alloy activity coefficient calculated using the MIVM model,in accordance with the gas-liquid phase equilibrium theory,Ti-Al,Ti-V,Al-V drawing and Ti-Al-V alloy system phase equilibrium diagram,and predict alloy ingredients.The results show that the forecasting by ternary alloys is more accurate than that predicted by binary alloys.Secondly,this paper fully considers the system pressure,corrects the Langumir formula,calculates alloying ingredients and compares them with the experimental values to determine the A1 and V ingredient model equations.The results show that the Langmuir formulas before and after the correction can all be experimentally predicted.Theoretically,the revised formula is closer to the actual forecasting according to the ternary alloy than the prediction based on the binary alloy.Finally,by comparing the thermodynamic prediction and the dynamic prediction effect,the dynamically modified Langumir formula is determined as the best prediction method.At the same time,the volatilization mechanism of A1 was studied by kinetic method.The results show that the process of metal evaporation in the alloy includes four processes:With the increase of temperature,the diffusion of Al atoms in the liquid phase and the transmission of the interface volatilization increase.The higher the temperature,the closer the two become.When the temperature is lower,the mass transfer coefficient of the interfac.e volatilization is smaller than that of the liquid phase.The diffusion coefficient.Therefore,when the temperature is low,the interface volatilization is the limiting part of the volatilization of the Al element,As the temperature increases,it is limited by both the interface volatilization and the diffusion in the liquid phase.