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

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 degrees C for 15 min and casting at 720 degrees 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 + delta-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.