Rampulla D M, Mancinelli C M, Brunell I F, Gellman A J
Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213, USA.
Langmuir. 2005 May 10;21(10):4547-53. doi: 10.1021/la0469093.
The origins of the tribological properties and corrosion resistance of amorphous and quasicrystalline approximant alloys have been studied by comparing their properties in thin Al-Cu-Fe alloy films with compositions lying near the quasicrystalline region of the ternary compositional phase diagram. Six sputtered thin films of an Al-Cu-Fe alloy were studied using X-ray diffraction, X-ray photoemission spectroscopy (XPS), and an in situ ultrahigh vacuum (UHV) tribometer. The films were annealed in UHV to induce the formation of orthorhombic, rhombohedral, and amorphous bulk structures. The properties of these thin films were then determined in the same UHV apparatus without exposing the films to air. The rates of surface oxidation by H2O and O2 were measured using XPS. Although the oxidation rates and oxide thicknesses were dependent on the oxidant, they were not sensitive to the structures of the films. Friction was measured between identical samples in sliding contact. The friction coefficients (micros = 0.36 +/- 0.11 to 0.56 +/- 0.08) were comparable to those observed in other experiments using quasicrystals and approximants in UHV; however, there was no strong correlation between the friction coefficients and either the film structure or the degree of surface oxidation. These results suggest that the tribological and corrosion resistance properties of these quasicrystalline approximant alloys are not directly connected to crystalline structure.
通过比较位于三元成分相图准晶区域附近的Al-Cu-Fe合金薄膜的性能，研究了非晶态和准晶近似合金的摩擦学性能和耐腐蚀性的起源。使用X射线衍射、X射线光电子能谱（XPS）和原位超高真空（UHV）摩擦计研究了六种Al-Cu-Fe合金溅射薄膜。这些薄膜在超高真空下退火，以诱导正交、菱面体和非晶态块状结构的形成。然后在同一超高真空设备中测定这些薄膜的性能，而不将薄膜暴露在空气中。使用XPS测量了H2O和O2引起的表面氧化速率。尽管氧化速率和氧化物厚度取决于氧化剂，但它们对薄膜结构不敏感。在滑动接触的相同样品之间测量了摩擦力。摩擦系数（微观 = 0.36 +/- 0.11至0.56 +/- 0.08）与在超高真空下使用准晶体和近似晶体的其他实验中观察到的摩擦系数相当；然而，摩擦系数与薄膜结构或表面氧化程度之间没有很强的相关性。这些结果表明，这些准晶近似合金的摩擦学和耐腐蚀性与晶体结构没有直接联系。
