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A connection between hot-dip galvanized 45 steel and AZ91D was achieved by liquid-solid compound casting to achieve one material with a better mechanical performance and a light weight. The microstructure and properties of galvanized-steel/AZ91D bimetallic materials were investigated in this study. A scanning electron microscopy (SEM), an energy dispersive spectroscopy (EDS), and an X-ray diffraction (XRD) were applied to analyze the microstructure evolution and formation mechanism of the galvanized 45 steel/AZ91D interface zone which could be divided into three layers. Among three different layers, the layer close to AZ91D was composed of α-Mg and an eutectic structure (α-Mg + MgZn). The intermediate layer was comprised of an eutectic structure (α-Mg + MgZn), and the layer adjacent to 45 steel consisted of α-Mg and FeAl3. Furthermore, galvanized-45 steel/AZ91D bimetallic material had better shear strength than the bare-45 steel/AZ91D metallic material which can indicate that owing to the formation of metallurgical bonding, the adhesive strength of galvanized-steel and AZ91D was improved to 11.81 MPa. In addition, the fact that corrosion potential increased from −1.493 V to −1.143 V and corrosion current density changed from 3.015 × 10−5 A/cm2 to 1.34 × 10−7 A/cm2 implied that the corrosion resistance of galvanized-steel/AZ91D was much better than AZ91D.

The austempered ductile iron was austenitized at 900 °C for 1 h and quenched in an isothermal quenching furnace at 380 °C and 280 °C, respectively. This paper aims to investigate the effects of bainite on wear resistance of austempered ductile iron (ADI) at different loads conditions. The micro-structure and phase composition of ADI was characterized and analyzed by metallographic microscope (OM), X-ray diffractometer (XRD) and scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS). The results showed that the volume fraction of retained austenite in ADI is reduced with the increase of austenitizing temperature. Meanwhile, the two kinds of ADI samples showed varied wear resistance when they were worn at different loads conditions. For wearing at a load of 25 N, the wear resistance of ADI mainly depends on matrix micro-hardness. Thus, ADI with lower bainite structure has higher hardness and leads to better wear resistance. When wearing at a load of 100 N, the increase of micro-hardness of upper bainite was significant. As a consequence, upper bainite showed superior friction and wear behavior. It was also found that the form of wear behavior of ADI changed from abrasive wear to fatigue delamination as the wear load increased from 25 N to 100 N according to the observation on worn surface.

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.

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