In the present work, a series of Nb-Ta-W and Nb-Ta-W-Hf refractory multi-principal element alloy thin films were fabricated by multi-target direct current magnetron co-sputtering. The ternary Nb-Ta-W thin films displayed a single BCC solid solution structure with the flake-like surface morphologies and a double-layer structure for cross sections with a columnar upper layer and an amorphous layer near the substrate. The average grain size was 16–30 nm estimated by Williamson-Hall mode and the surface roughness Ra value was 5–7 nm. These ternary thin films had excellent mechanical properties with the hardness values of 25–29 GPa and elastic modulus of 294–325 GPa. After Hf was introduced into the equiatomic NbTaW thin film, the plane view morphology of the NbTaWHf_0.6 thin film changed into a fine granular structure, but with a small amount of round particles on the surface. With the further increase of Hf content, the surfaces of the thin films kept being granular structure, but round particles disappeared on the surface of NbTaWHf film, and appeared again on the surfaces of high Hf content films with the increasing number. The cross sections of all Hf-contained thin films were smooth, dense and featureless. Meanwhile, the Ra of Nb-Ta-W-Hf thin films was significantly reduced, ranging from 0.92 to 1.47 nm. All Hf-contained thin films formed amorphous structure. The hardness of Nb-Ta-W-Hf thin films exceeded 19 GPa, and the NbTaWHf thin film had the highest hardness of 22.1 ± 1.3 GPa and elastic modulus of 239.3 ± 6.5 GPa, respectively. Due to the amorphous structure, Nb-Ta-W-Hf thin films exhibited excellent corrosion resistance. The corrosion current density was about two orders of magnitude lower than that of 304 stainless steel, and the polarization resistance was much higher than that of 304 stainless steel.

本工作采用多靶直流磁控共溅射制备了一系列 Nb-Ta-W 和 Nb-Ta-W-Hf 难熔多主元素合金薄膜。三元Nb-Ta-W薄膜呈现出具有片状表面形态的单一BCC固溶体结构和具有柱状上层和靠近衬底的非晶层的横截面的双层结构。通过 Williamson-Hall 模式估计的平均晶粒尺寸为 16-30 nm，表面粗糙度 Ra 值为 5-7 nm。这些三元薄膜具有优异的机械性能，硬度值为 25-29 GPa，弹性模量为 294-325 GPa。将 Hf 引入等原子 NbTaW 薄膜后，NbTaWHf 的平面形貌为_0.6薄膜变为细粒状结构，但表面有少量圆形颗粒。随着Hf含量的进一步增加，薄膜表面保持颗粒状结构，但圆形颗粒在NbTaWHf薄膜表面消失，随着数量的增加，又出现在高Hf薄膜表面。所有含 Hf 薄膜的横截面均光滑、致密且无特征。同时，Nb-Ta-W-Hf薄膜的Ra显着降低，范围从0.92到1.47 nm。所有含Hf的薄膜都形成了非晶结构。Nb-Ta-W-Hf薄膜的硬度超过19 GPa，NbTaWHf薄膜的最高硬度分别为22.1±1.3 GPa和239.3±6.5 GPa。由于无定形结构，Nb-Ta-W-Hf薄膜表现出优异的耐腐蚀性。腐蚀电流密度比304不锈钢低两个数量级左右，极化电阻远高于304不锈钢。