در طي عمليات آنيل در كوره خلا به روش پراش اشعه ايكس Ti- 6 AL- 4 V بررسي آلودگي سطحي آلياژ

A Study of Surface Contamination During Annealing in a Vacuum Furnace on Ti-6A1-4V Alloy by The X-Ray Diffraction Technique

In this research the contaminated surfaces of a Ti -6A1-4V alloy, which produced by stress, relieve annealing in a furnace having a vacuum of 2* 10-4 mm mercury, were investigated by the X - Ray Diffraction (CRD) technique. For this purpose, test samples were heat treated at 500 °C for one hour and 550°C, 600°C, 650°C, 800°C for five hours. The method of identifying equilibrium phases in this alloy was derived and the lattice parameters of these phases were calculated by the use of diffractometer. Comparison of the calculated results with the values given in source books shows the validity of our results. Study of the effect of the annealing tern peratures on lattice parameters of the a phase showed that at temperatures of 650°C and higher, desolution of oxygen in this phase increases the volume of crystal lattice. It is not possible to get rid of surface contamination completely by removing the surface layer with the colour change. XRD Analysis of the surface oxide layer showed that the TiO is the first oxide formed in the surface when annealing heat treatment is done at 800 °C for 5 hours. The lattice parameter of TiO was measured to be 4.294 A.