en گروه سطح پوشش و خوردگی Surface Coatings and Corrosion Technical Note Technical Note <b><i><font face="TimesNewRomanPS-BoldItalicMT" size="1"><font face="TimesNewRomanPS-BoldItalicMT" size="1"><p align="left">Abstract: </p><p align="left">activity gas diffusion process has been investigated in this research. Effects of coating temperature and aluminum</p><p align="left">concentration in powder mixture on formation mechanism were studied using optical and scanning electron</p><p align="left">microscopes, EDS and X-ray diffraction (XRD) techniques. For this purpose two different packs containing 1 and 2</p><p align="left">wt% aluminum powder, were used for coating the samples at two temperatures, 850ºC and 1050ºC. The ratio of Al to</p><p align="left">activator was kept constant in both packs. By increasing the Al content in high activity powder mixture, the</p><p align="left">concentration of diffused Al increased in the coating layers, and the thickness of coating increased. At 1050ºC as the</p><p align="left">rate of diffused Al to the interdiffusion zone increased, this zone gradually transformed to outer coating phases. At</p><p align="left">850ºC coating formed by inward diffusion of Al, but at 1050ºC it was initially formed by inward diffusion of Al followed</p><p align="left">by outward diffusion of Ni.</p></font></font><font face="TimesNewRomanPS-ItalicMT" size="1"><font face="TimesNewRomanPS-ItalicMT" size="1">Formation mechanism of an aluminide coating on a nickel base superalloy IN738LC via a single step high</font></font></i></b> Gas Phase Aluminizing, Formation Mechanism, high Activity, Effect of Temperature, Inward and outward diffusion 42 49 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-3-130&slc_lang=en&sid=1 H. Rafiee*, * h_rafiee@metaleng.iust.ac.ir 180031947532846001159 180031947532846001159 Yes S. Rastegari 180031947532846001160 180031947532846001160 No H. Arabi 180031947532846001161 180031947532846001161 No M. Mojaddami 180031947532846001162 180031947532846001162 No