Electrodeposited zinc-nickel alloy coatings have been widely adopted for surface treatment of automobile body steel sheet for high corrosion resistance. The corrosion behavior of the coatings has been related with the components of nickel, and the zinc-nickel alloy passive coatings have much higher corrosion resistance than that of zinc-nickel alloy coatings. In the present paper, the corrosion resistance behavior of the zinc-nickel alloy coatings obtained by new process and formulation has been studied by means of the electrochemistry test and neutral salt spray test. And it is discovered that the properties of corrosion resistance of zinc-nickel alloy passive coatings were better than that of zinc passive coatings, Cadmium passive coatings and alloys of electrodeposited cadmium-titanium. The components of corrosion productions, in terms of X-ray diffraction (XRD), are mainly ZnO, ZnCl 2 ·4Zn(OH) 2 and small quantity of 2ZnCO 3 · 3Zn(OH) 2 . The component of zinc-nickel alloy coatings has been investigated with Glow Discharge Optical Emission Spectrometry (GDA-750). And it is found that as the thickness of zinc-nickel alloy coatings increases, the component of zinc increases from beginning to end, but the peak value of nickel appears and an enrichment of nickel in the coatings comes into being. Because the electrodeposited zinc-nickel alloy coatings exhibit different alloy phases as a function of their alloy composition, in this paper, the crystal structure changing with the different component of nickel has been studied in terms of XRD. The result shows that electrodeposited zinc-nickel alloy has different phases: α-phase, a solid solution of zinc in nickel with an equilibrium solubility of about more than 79% nickel; γ -phase, an intermediate phase with a composition Ni 5 Zn 21 ; η-phase, a solid solution of nickel in zinc with less than 5% nickel; and δ-phase (Ni 3 Zn 22 ) appeared from η-phase to α-phase with increasing content of nickel.

A substantial undercooling up to 250 K was produced in the IN718 superalloy melt by employing the method of molten salt denucleating, and the microstructure evolution with undercooling was investigated. Within the achieved undercooling, 0–250 K, the solidification microstructure of IN718 undergoes two grain refinements: the first grain refinement occurs in a lower range of undercooling, which results from the ripening and remelting of the primary dendrite, and at a larger range of undercooling, grain refinement attributes to solidification shrinkage stress and lattice distortion energy originating from the rapid solidification process. A ‘lamellar eutectic anomalous eutectic’ transition was observed when undercooling exceeds a critical value of ∼250 K. When undercooling is small, owing to niobium enrichment in interdendrite, the remaining liquid solidifies as eutectic ( γ+Laves phase); whereas, if the undercooling achieves 250 K, the interdendrite transforms from eutectic ( γ+Laves phase) to Laves phase, which results from the formation of divorced eutectic arising from the huge variance of the growth velocities of γ and Laves phases.

Ni-based TiN-TiC composite coating was fabricated on DZ125 superalloy surface by laser cladding. The phase constitution and microstructures were investigated by means of X-ray diffraction (XRD), optical microscope (OM) and scanning electron microscope (SEM). Microhardness measurements and wear experiments without lubrication were also accomplished. The experimental results showed that a pore- and crack-free coating with metallurgical bonding to the substrate was obtained. Solidification morphologies along the section of the coating varied from directional dendrite in the interface to random dendrite in the surface. The coating was mainly composed of γ-Ni, M23C6, TiN, TiC particles and a small amount of NiTi, respectively. The average microhardness of 705HK for the coating was 2.3 times higher than that of the substrate. Wear tests indicated that wear resistance of the coating was significantly improved compared with that of the substrate. The improvement in hardness and wear resistance was attributed to TiN and TiC phase and chromium carbide uniformly dispersed in the matrix of the Ni-based TiN-TiC composite coating.

Using as high strength and corrosion resistance of tubing material, the wear properties of TC4 alloy and P110 tubing steel were comparatively studied, the differences and similarities were analyzed that are weight loss of wear rate and friction coefficient and topography of wear mark, the wear mechanism was discussed. The results showed that the topography of TC4 alloy and P110 tubing steel are different entirely, TC4 alloy is furrow, P110 tubing steel is wear pit, the wear resistance of P110 tubing steel is excelled obviously than TC4 alloy, the wear mechanism of TC4 alloy is delamination wear and adhesive wear and fatigue wear. The wear mechanism of P110 tubing steel is delamination wear and abrasive wear.

Directional solidification technique permits materials to grow along specific orientation, in order to obtain mechanical and/or physical anisotropy. The present research attempts to introduce the research work in the field of processing of some advanced materials by innovative directional solidification techniques performed at State Key Laboratory of Solidification Processing and with author’s intended research work. The paper deals with the specific topics on state of the art of directional solidification: single crystal superalloy and Nd-Fe-B alloys under high thermal gradient, Cu-Ni alloys under deep supercooling of the melt. The relevant solidification phenomena, such as morphological evolution, crystal growth for multi-phases in the processing of directional solidification, are discussed briefly. The trends of developments of directional solidification techniques are also prospected.