纯钛和镍包埋渗铝的热力学研究(英文)

分别在敞开和密闭系统中进行纯钛和纯镍的气相渗铝实验。渗铝实验在1100℃下进行3h,包埋粉末含10%Al、5%NH4Cl和85%Al2O3。在敞开条件下,渗铝后纯钛的表面会生成α(Al)固溶体,样品的质量损失达到32.37%。然而,在密闭条件下,纯钛样品的表面生成TiAl3层和α(Al)固溶体,没有质量损失。热力学分析表明,在敞开条件下对纯钛渗铝时,会生成钛的氯化物,导致其质量减少。而在密闭条件下,由于生成的氯化物会达到平衡状态而使生成反应停止。相反,无论是在敞开或密闭条件下,纯镍样品都可以进行表面渗铝,不会导致质量损失。在两种状态下,镍的表面都生成了AlNi和Ni3Al相。

Thermodynamic study on pack aluminizing systems of pure titanium and nickel

Gas aluminizing of pure titanium and nickel samples was carried out in open and closed systems. All the samples were aluminized at 1100 °C for 3 h using pack containing 10%Al+5%NH₄Cl+85%Al₂O₃. Although an α solid solution of Al in Ti was formed on the surface of titanium samples treated in the open set-up, but the samples experienced a mass loss of 32.37%. However, the results of titanium samples treated in the closed set-up showed that a TiAl₃ layer and some α solid solution were formed on the surface of these samples without any reduction in mass. Thermodynamic analysis demonstrated that the mass loss of treated titanium samples in the open set-up is due to the continuous formation of titanium chlorides during aluminizing process. Nevertheless, running the experiments in the closed system indicated that the corrosion of titanium samples vanished due to attaining the equilibrium condition. On the contrary, it was observed that nickel samples can be successfully pack aluminized without any mass loss in both open and closed systems. The presence of NiAl and Ni₃Al phases on the surface of treated nickel samples was confirmed by XRD and EPMA results in both set-ups.