Study On The Diffusion Process Of Al/Ti Liquid-Solid Interface

The aluminum-titanium composite material not only has various advantages of titanium and aluminum,but also has lower density than titanium and excellent thermal conductivity of aluminum.Therefore,it is widely used in aerospace,petrochemical,nuclear energy,construction and many other fields.At present,the production methods of aluminumtitanium composite sheets mainly include rolling bonding method,explosive welding method,vacuum diffusion welding method,continuous casting and rolling method,and the like.Among them,the continuous casting and rolling method belongs to the liquid-solid composite method,aluminum and titanium are composited in the casting and rolling zone.Compared with the conventional method,it has the advantages of short process,less investment,high efficiency,etc,and has obvious advantages and great process realization potential.The diffusion and reaction process of aluminum and titanium in the casting zone will greatly affect the joint performance of the aluminum-titanium composite plate.Therefore,studying the diffusion and reaction process of aluminum and titanium in the compounding process will help to obtain an aluminum-titanium composite board with excellent performance.In this paper,pure titanium strip and pure aluminum were selected as experimental materials.According to the relevant process parameters of continuous casting and rolling process,the process parameters of aluminum/titanium liquid-solid interface diffusion were determined.The effects of different aluminum liquid temperature,different holding time,different preheating temperature of titanium plate,uniform magnetic field and pulse current on the microstructure of Al/Ti liquid-solid interface and the thickness of diffusion-solution zone were studied.The paper obtained the following results:(1)Whether it is a normal temperature titanium plate or a titanium plate preheated to 150?,the thickness of the Al/Ti diffusion-solution zone increases with the increase of the holding time after holding at 680?,700?,720? aluminum melt for different time.The microstructure at the interface is basically the same,and no obvious compound layer is visible.(2)When the holding time is 1s,there is no interdiffusion at the aluminum-titanium interface;when the holding time exceeds 3s,the thickness of the Al/Ti diffusion-solution zone is basically a power function relationship with the holding time,and the growth index of the diffusion-dissolved layer is between 0.25 and 0.5,indicating that the growth of the Al/Ti diffusion-solution zone is jointly controlled by grain boundary diffusion and bulk diffusion;under the experimental conditions of this paper,TiAl3 is the earliest precipitated at the interface and is the only precipitated phase.(3)Under the application of a magnetic field in the diffusion process,the thickness of the Al/Ti diffusion-solution zone becomes thin,and the interface becomes uneven.The magnetic field increases the activation energy required for atomic diffusion,thereby inhibiting the growth of the Al/Ti diffusion-solution zone.(4)After the pulse current is applied in the diffusion process,the thickness of the Al/Ti diffusion-solution zone becomes thick,and the incubation period of TiAl3 is shortened.When the holding time is 2s;intermetallic compounds appear at the interface,and some intermetallic compounds diffuse into the aluminum matrix from the interface.The forced convection generated by the pulse current in the aluminum melt effectively promotes the growth of the Al/Ti diffusion-solution zone.(5)Within the parameters of this experimental study,under the condition of aluminum alloy melt temperature of 680?720?,by controlling the conditions of the external field and the preheating of the titanium plate,the requirements of the casting and rolling compound process can be met,and the metallurgical bonding of the titanium-aluminum interface can be realized.