In this research the oxidation resistance at high temperature of a TiAl-based alloy has been improved by hot-dipping the alloy in molten aluminium and by performing an interdiffusion process. After selecting the best process parameters, a compact TiAl3 coating characterized by an almost constant thickness was formed on the surface. Isothermal oxidation tests, carried out at 900, 950 and 1000 °C, showed that the coated alloy is able to form a continuous and thin alumina layer that is very protective. Microstructural investigations highlighted that, above 900 °C, long residence times at high temperature determine the diffusion through the TiAl3 layer of Cr that favours migration toward the outer surface of Al and thus the formation of a self-healing alumina layer.Graphical

Mo(Si,Al)2 with different yttrium (Y) additions (up to 2 at.%) was synthesised by dry powder mixing followed by compaction and sintering. In as-sintered materials, Y was present as yttrium aluminium garnet. The materials were exposed in air at 1500 °C for up to 250 h to study the effect of Y on oxidation behaviour. The oxides formed were investigated using scanning electron microscopy (SEM)-based techniques and X-ray diffraction. While the Y-free Mo(Si,Al)2 formed a scale consisting of Al2O3 and a small amount of mullite, the Y-containing samples formed oxides containing both yttrium silicate and larger fractions of mullite, in addition to Al2O3. Oxidation rate, scale spallation, as well as the evaporation of Mo, all increased with Y addition.

Modern EAF steelmaking employs scrap as its primary source of raw material. Different sources of scrap have varying levels of residuals, which can negatively influence product properties, performance, and surface quality. The presence of some residuals, such as Cu and Ni in controlled quantities, can also positively impact steel performance for some applications. It is also well known that interactions between residuals and alloying elements in steel can modify the structure of scale formed during slab reheating prior to hot rolling. These changes in the scale structure can influence scale removability. In this study, the effect of varying Cu concentrations in a low alloyed Mn and Si containing steel was examined to investigate its impact on scale removability. Laboratory studies were performed with simulated reheating and descaling conditions that mimic the conditions used in industrial practices. The scale structure that formed during reheating in the combustion atmosphere was investigated using SEM/EDX analysis. A special laboratory water jet descaling device was used to evaluate scale removability at three different hydraulic impact factors. The results showed that Cu at different levels significantly modified scale structure that formed, particularly the internal scale layers, which affected scale removability at different applied descaling impact factors. The effects of Cu level and descaling impact factor on scale removability is discussed.