Ti60高温钛合金氧化行为研究

Oxidation Behavior of Near α-Titanium Alloy Ti60

摘要:

研究Ti60高温钛合金在600~750 ℃范围内的氧化行为。氧化增重试验及XRD、SEM分析结果表明，Ti60合金在600~750 ℃范围内氧化0~100 h条件下，由Wagner的氧化经验公式计算得氧化指数n在1~2之间，氧化激活能为256 kJ/mol，氧化符合线性-抛物线混合规律。在600 ℃氧化100 h及750 ℃氧化10 h，氧化产物为TiO2，经750 ℃、100 h长时间氧化后，表面有少量Al2O3生成，氧化物优先沿原始β晶界形核。氧除了会在试样表面形成氧化层外，还会向基体中扩散形成脆性富氧层，从而影响合金力学性能。随着氧化温度的升高和时间的延长，富氧层厚度增厚。

Abstract:

Air oxidation behavior of Ti60 alloy was studied in the temperature range from 600 oC to 750 oC. In addition to the determination of the oxidation kinetics by mass gain measurements, the morphology of the scales formed was observed by SEM and the phases present in the scales were characterized by X-ray diffraction. Results show that under the condition of oxidation at 600-750 oC for 0-100 h, the oxidation exponent n is between 1 and 2 calculated by oxidation experience formula of Wagner, the total oxidation energy is 256 kJ/mol, and the oxidation kinetics follows the linear-parabolic law. When Ti60 alloy was oxidized at 600 oC for 100 h or at 750 oC for 10 h, the oxidation product is TiO2, while there was a little Al2O3 on the surface when the alloy was oxidized at 750 oC for 100 h. The oxides were preferentially formed at the grain boundaries of the alloy. Besides the oxidation layer on the sample surface, oxygen also dissolves into the matrix to form brittle oxygen-enriched layer resulting in the mechanical property change. The oxygen-enriched layer was thickened with the increase of oxidation temperature and prolonging of the oxidation time.