采用选区激光熔化技术制备的TC4钛合金的高温氧化行为研究

High Temperature Oxidizing Behavior of TC4 Titanium Alloy Fabricated by Selective Laser Melting

采用选区激光熔化技术制备了尺寸为15 mm×15 mm×15 mm的TC4(Ti-6Al-4V)钛合金试样。试样在箱式烧结炉中进行了550℃氧化48 h和96 h的试验。采用光学显微镜、X射线衍射仪、扫描电子显微镜、能谱仪和显微硬度计等检测了试样的氧化增重,氧化层的相结构、成分变化,表面和截面形貌,以及硬度梯度。结果表明:合金在550℃的氧化速率随着氧化时间的增加呈抛物线状变化;在550℃氧化48 h和96 h的试样的增重分别为0.178 mg/cm^(2)和0.263 mg/cm^(2),其氧化层厚度分别为2μm和3μm,主要由Ti、TiO_(2)和少量Al_(2)O_(3)组成;在表面以下相同深度处的硬度,550℃氧化96 h的试样高于氧化48 h的试样。

TC4(Ti-6 Al-4 V) titanium alloy specimens measuring 15 mm by 15 mm by 15 mm were fabricated by a selective laser melting technology. The specimens were oxidized in a box sintering furnace at 550 ℃for 48 h and 96 h, and then were tested for the oxidation weight growth, the phase structure, surficial and sectional forms and composition change of the oxide layer,and hardness gradient by means of optical microscope, X-ray diffractometer, scanning electron microscope, spectrometer and micro-hardness tester. The results showed that(a)oxidation rate of the alloy at 550 ℃changed in the form of parabola with the increase in oxidizing time;(b)weight growths of the specimens oxidized at 550 ℃for 48 h and 96 h were 178 and 0.263 mg/cm^(2)respectively, and oxide layers on them were as thick as 2 and 3 μm respectively, and consisted largely of Ti, TiO_(2)and a small amount of Al_(2)O_(3)and(c) the specimen oxidized at 550 ℃for 96 h displayed higher hardness than did the specimen oxidized at 550 ℃ for 48 h at the same depth from the surface.