The Research On Process Of Al-Ti-C Master Alloy Prepared Under The Action Of Are Temperature

Grain refinement can improve the strength of metal and enhance the uniformity of its microstructure.With their good grain refining effect,aluminum alloy grain refiners are widely used in industrial production during the process of melting and casting of aluminum and its alloys.There are many kinds of intermediate alloys,among which Al-Ti-B is relatively practical in industry production.Compared to Al-Ti-B,Al-Ti-C can refine high-strength aluminum containing Zr,Cr,Mn and other elements,which has a better refining effect,and can overcome the disadvantages of the Al-Ti-B refinement process.The main reason why difficult to prepare Al-Ti-C master alloys is that the solubility of C in Al is extremely low,and it is easy to float to the surface of Al liquid to adsorb oxygen and hinder the reaction between C and Ti to generate Ti C.In this paper,Al-Ti-C master alloy was prepared by the arc produce instantaneous high temperature,The synthesis of Al-Ti-C master alloy and its refinement of aluminum was studied by means of scanning electron microscopy?SEM?,X ray diffraction?XRD?,energy spectrum analysis?EDS?to analysis.The phase compositions and microstructures of Al-Ti-C master alloys prepared under the high temperature arc were studied.Under the high temperature of the arc,Ti and C are evenly distributed in the aluminum liquid.The instantaneous temperature of the arc can reach 1500°C.The Al-Ti-C system forms a local high-temperature zone and promotes the reaction between C and Ti to form Ti C.The effect of raw materials on the Al-Ti-C master alloy was investigated.Graphite as a raw material contains more Ti Al₃ and Ti C in Al-Ti-C than C powder as a raw material,and there is no C residue.In the case of arc-heated Al-Ti-C prepared by adding Ti C,a smaller amount of Ti Al₃ and a piece of Ti C are accumulated,and Ti C is not desirable as a raw material.The effects of graphite pretreatment,aluminum liquid temperature,current,Ti/C ratioandholdingtimeontheas-preparedAl-Ti-Cmasteralloywere investigated.Graphite pretreatment can increase the wettability between Al and C and the flowability of C in Al-Ti-C.The composition and phase size of Al-Ti-C prepared by arc high temperature at different aluminum liquid temperatures are quite different.From 800°C to 900°C,the size of Ti Al₃ increases with increasing temperature,and the content of Ti Al₃ and Ti C decreases with increasing temperature.At the current of 25A,contains only Al and Ti in Al-Ti-C dissolved in the aluminum melt.At the current of 50A,Al-Ti-C contains Ti Al₃ and a smaller amount of Ti C.At the current of 75A,and the temperature released by the arc can promote the reaction of Al-Ti-C system to produce Ti Al₃ and Ti C.At the current of 100A,and the instant temperature of the arc discharge is too high.The prepared Al-Ti-C contains Ti C and a smaller amount of Ti Al₃.The experimental results show that the Al-Ti-C master alloy prepared by with graphite the 10%HF acid treatment and titanium powder under the conditions of 75A current and 800°C temperature is the best.As-prepared Al-Ti-C with high temperature arc was added to industrial pure aluminum to analyze the refining effect.The industrial pure aluminum grains after adding Al-Ti-C were refined from the original 800?m to 90?m.The effect of the amount of refiner added,temperature,holding time,and niobium on the refinement of pure aluminum were studied.When the addition amount of refiner is 0.4%,the temperature is 740°C and the holding time is 30min,the refining effect of pure aluminum is best.The shapes of“circles”appeared in Al-Ti-C refined industrial pure aluminum.The shapes of“circles”contributes to the refinement of pure aluminum.The main reason is that there is an effective nucleation within the"halo"of the grain growth front,which suppresses the growth of the surrounding grains and produces a refinement effect.