| Summary: | 碩士 === 國立聯合大學 === 材料科學工程學系碩士班 === 97 === Binary Ni-Al alloy coatings were fabricated by magnetron co-sputtering technique with multi targets of pure Ni and Al metals. The chemical composition variation of the coatings in terms of sputtering input power modulation and substrate deposition temperature variation was investigated. The Ni-Al coatings with Al contents ranged from approximately 2.7 to 62.9 at.% could be manipulated through multi-gun sputtering. The as-deposited Ni-Al coatings possessed crystalline and nano-crystalline microstructures with respect to deposition input powers, substrate temperatures, and working pressures. Significant crystallization feature of disordered Ni(Al) (γ) and ordered AlNi3 (γ′) , Al3Ni (ε), and Al3Ni2 (δ) phases were observed for the Ni-Al coatings with the variation in sputtering input powers and substrate deposition temperatures. The phase evolution analysis of Ni-Al coatings indicated the good thermal stabilities for the coatings under both as-deposited and post annealed states. A thermodynamic quasi-equilibrium state formed at as-deposited state for the Ni-Al coating was confirmed. The dependency of surface morphologies and grain sizes on the variation of input powers, substrate deposition temperatures was intensively discussed. Through nano-indentation analysis, the coatings with Ni(Al) and AlNi3 microstructure feature exhibited a higher hardness. The formation of Ni(Al) and AlNi3 phases was the strengthening mechanism for Ni-Al coatings under high energy input during sputtering. The variation in hardness was attributed to the crystallite size and microstructure evolution. In order to figure out the effect of Al in properties for Ni-based coatings, the Ni-P and Ni-P-Al coating systems were compared with Ni-Al binary coating. The microstructure, phase evolution, and related properties of the Ni-P, Ni-P-Al, and Ni-Al coatings were discussed.
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