Ni-Ti合金在650-850℃空气中的氧化行为研究

OXIDATION BEHAVIOR OF Ni-Ti ALLOYS AT 650-850℃ IN AIR

研究了 Ｎｉ；Ｎｉ－５Ｔｉ，Ｎｉ－１０Ｔｉ及 Ｎｉ－１５Ｔｉ（质量分数，％，下同）合金在 ６５０－８５０℃空气中的氧化行为．结果表明，在６５０℃氧化时，Ｎｉ－Ｔｉ合金的氧化速率明显低于纯Ｎｉ；合金表面形成连续的以ＴｉＯ２为主的氧化膜；随着氧化温度的升高，Ｎｉ－Ｔｉ合金的氧化速率逐渐增加至接近或大于纯 Ｎｉ，合金表面形成由ＮｉＯ；ＮｉＴｉＯ３和 ＴｉＯ２组成的外氧化层，同时沿合金基体发生 Ｔｉ的内氧化．在 Ｎｉ－１０Ｔｉ和 Ｎｉ１５Ｔｉ合金（内）氧化前沿，原始合金的二相组织已退化成单相组织．进一步讨论了合金氧化机制。

The oxidation behaviors of Ni, Ni-5Ti, Ni-10Ti and Ni-15Ti (mass fraction, %) at 650-850 ℃ in air have been studied. The results indicate that the oxidation rates of Ni-Ti alloys are smaller than that of pure Ni at 650 ℃, and on their surface formed a continuous scale consisting mainly of TiO2. With increasing the temperature, the oxidation rates of Ni-Ti alloys are increased to be close to or larger than that of pure Ni, on the surface of the alloys an external scale containing NiO, NiTiO3 and TiO2 formed, and within matrix of the alloys an iniernal oxidation region of titanium appeared. In addition, the two-phase structure of Ni-10Ti and Ni-15Ti alloys has been transformed into a single-phase structure along the frontier of (internal) oxidation. The oxidation mechanism of the alloys was also discussed.