The Influence of Tungsten Alloying Additions on the Passivity of Aluminum
The Influence of Tungsten Alloying Additions on the Passivity of Aluminum
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DOI：
10.1149/1.2085404
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发表时间：
1991-11
影响因子：
3.9
通讯作者：
B. Shaw;G. D. Davis;T. L. Fritz;B. J. Rees;W. C. Moshier
中科院分区：
文献类型：
--
作者：
B. Shaw;G. D. Davis;T. L. Fritz;B. J. Rees;W. C. Moshier
过渡金属如Mo、W、Ta、Cr和W可以显著提高Al的局部耐蚀性。由于这些元素在铝中的溶解度非常低，因此必须采用非平衡合金化方法，如溅射沉积，来生产单相合金。在Al中加入约9%的W可以使其点蚀电位向正方向移动多达2600 mV。这些非平衡合金的热处理导致第二相的析出，这对腐蚀性能是有害的，但不是灾难性的。对Al-W钝化膜的表面分析表明，在整个极化过程中，铝- w钝化膜都保持较薄的状态，并且无论外加电位如何，其氧化溶质含量都非常低。氧化后的W以WO{sub 2}和WO{sub 3}（或WO{sup {-}2}{sub 4}）的形式存在于膜中。本文的研究结果表明，W的加入并不是静电斥力或氧化溶质阻挡层机制导致Al钝化性的显著增强，相反，钝化膜中少量的氧化W可能与水合氧化铝结构协同作用，形成更强的保护膜。«少
Transition metals such as Mo, W, Ta, Cr, and W can be used to significantly enhance the localized corrosion resistance of Al. Since these elements exhibit very low solubilities in aluminum, a nonequilibrium alloying method, such as sputter deposition, must be used to produce single-phase alloys. The addition of approximately 9 atom percent W to Al can shift its pitting potential in the positive direction as much as 2600 mV. Heat-treatment of these nonequilibrium alloys results in the precipitation of a second phase that is detrimental, but not catastrophic, to corrosion performance. Surface analysis of the Al-W passive film formed as a function of applied anodic potential reveals that it remains thin throughout the polarization sequence and contains very little oxidized solute, regardless of the applied potential. The oxidized W present in the film is in the form of WO{sub 2} and WO{sub 3} (or WO{sup {minus}2}{sub 4}). The results of this paper reveal that the electrostatic-repulsion or oxidized-solute barrier-layer mechanisms are not responsible for the dramatic enhancement in the passivity of Al with the addition of W. Instead, the small amount of oxidized W in the passive film may interact synergistically with the hydrated aluminum oxide structure to formmore » a more protective film.« less