Improving Shear Strength of Ti/Mg Bimetal Composites Prepared by Hot‐Dip Aluminizing and Solid–Liquid Compound Casting

Abstract

It is a great challenge to achieve the joining between Ti and Mg for their low solid solubility and positive formation enthalpy value. To fabricate high strength TC4/AZ91D bimetallic composite with metallurgical bonding interface, Al coating is prepared on the surface of TC4 alloy by hot‐dip technology, and Al‐coated TC4/AZ91D bimetal is prepared by solid–liquid compound casting herein. The effect of the hot‐dip process on the thickness and composition of the Al coating on the TC4 sample is discussed. Process parameters including casting temperature and liquid‐to‐solid volume ratio are investigated. The results reveal that the shear strength of Al‐coated TC4/AZ91D bimetal reaches 48.5 MPa when hot dipping at 700 °C for 15 min and casting at 720 °C with the volume ratio of 24, while that of the sample without Al interlayer is only 19.1 MPa. The reason is due to the formation of Ti(Al, Mg)3 intermetallic compound and Al12Mg17 + δ‐Mg eutectic structure at the interface. The results are helpful for the further development of high strength Ti/Mg bimetal by combining hot‐dip technology and solid–liquid composite casting technology.

Effect of HEA/Al composite interlayer on microstructure and mechanical property of Ti/Mg bimetal composite by solid-liquid compound casting

“…at the interface between Ti and Mg, and the density of Al 12 Mg 17 phase in the Mg fusion zone increased with the increase of Al layer thickness. At the interface ofAl-coated TC4/AZ91D bimetal prepared by SLCC[18] eutectic structure were formed, with shear strength rising from19.1 MPa to 48.5 MPa compared with the sample without Al interlayer. It can be seen from the above studies that the formation of intermetallic compounds through the reactions of Al interlayer with Mg and Ti is the main reason for the metallurgical bonding.…”

“…Generally, adapting an interlayer between Mg and Ti is proved to be a realistic and economic approach. In our previous studies, interlayers Ni [15] , Cu [16] , Zn [17] , Al [18] have been applied to obtain the metallurgical bonding between Mg and Ti by SLCC. Among them, Al is an important alloying element of both titanium alloy and magnesium alloy.…”