Due to their unique mechanical, tribological, thermal, and anticorrosion properties, nickel-tungsten (Ni-W) alloy films have become indispensable for many industrial applications. The present study investigates the impact of W content on the microstructure and mechanical properties of Ni-W thin films. By co-sputtering of Ni and W on silicon wafers coated with a thin buffer layer (∼20 nm) of titanium (Ti), six Ni-W coatings were fabricated, ranging from pure Ni to pure W. The samples were characterized using energy dispersive spectroscopy, x-ray diffraction, scanning electron microscopy, atomic force microscopy, and microindentation. The results show that hardness of the Ni-W films is primarily a function of the W content, which changes the microstructure and surface morphology of the samples. When W concentration is smaller than 40 at. %, the Ni-rich samples have a face-centered cubic structure and the hardness increases with the W content. For the samples having 40 < W < 55 at. %, the sensitivity of the hardness to the W content becomes markedly low, which could be due to the presence of an amorphous phase. Finally, the impact of W addition on the hardness of the samples containing 55–80 at. % W is two times greater than that of W < 40 at. %. The extra hardening effect could be attributed to the dominancy of a solid solution hardened body-centered cubic W phase and electronic interaction between two transition metals. This sharp increase in the hardness leads to obtaining a high hardness of 21.9 ± 2.0 GPa for the Ni-79 at. % W film. The findings of this study show that solid solution strengthening could be considered the main hardening mechanism of these films.

中文翻译：

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钨含量对磁控共溅射制备硬Ni-W薄膜的微观结构和表面形貌的影响

由于其独特的机械，摩擦，热和防腐性能，镍钨（Ni-W）合金膜已成为许多工业应用必不可少的材料。本研究调查了W含量对Ni-W薄膜的微观结构和力学性能的影响。通过在镀有钛（Ti）薄缓冲层（〜20 nm）的硅片上共溅射Ni和W，制得了从纯Ni到纯W的六种Ni-W涂层。使用能量对样品进行表征色散光谱，X射线衍射，扫描电子显微镜，原子力显微镜和显微压痕。结果表明，Ni-W膜的硬度主要是W含量的函数，这改变了样品的微观结构和表面形态。当W浓度小于40at。％，富镍样品具有面心立方结构，并且硬度随W含量的增加而增加。对于40 <W <55 at的样品。％，硬度对W含量的敏感性显着降低，这可能是由于非晶相的存在。最后，添加钨对55–80 at的样品硬度的影响。％W是W <40 at的两倍大。％。额外的硬化效果可以归因于固溶硬化的以体心为中心的立方W相的固溶以及两种过渡金属之间的电子相互作用。硬度的这种急剧增加导致Ni-79 at在21.9±2.0 GPa的高硬度。％W膜。这项研究的结果表明，固溶强化可以被认为是这些薄膜的主要硬化机理。