Structural transformations in air heated Al-Cr powder compacts

Abstract

In this study, structural changes in aluminum-chromium powder compacts were considered during exposure in the air at 500 °C. The samples were obtained by pressing the mixture of aluminum and chromium powders. The studies were carried out with using the X-ray diffraction and the metallographic analysis and by measuring the weight gain of the samples. It was established that the value of the specific mass gain has a complex and ambiguous dependence on the initial porosity of Al-Cr compacts due to phase transformations in powder mixtures. At short-term (up to 30 minutes) 500 °C air heating of the porous compacts significant oxidation does not occur. However, at the long-term exposure at 500 °C the reaction diffusion between aluminum and chromium occurs resulting in Al13Cr2 intermetallic formation and compacts swelling.In this study, structural changes in aluminum-chromium powder compacts were considered during exposure in the air at 500 °C. The samples were obtained by pressing the mixture of aluminum and chromium powders. The studies were carried out with using the X-ray diffraction and the metallographic analysis and by measuring the weight gain of the samples. It was established that the value of the specific mass gain has a complex and ambiguous dependence on the initial porosity of Al-Cr compacts due to phase transformations in powder mixtures. At short-term (up to 30 minutes) 500 °C air heating of the porous compacts significant oxidation does not occur. However, at the long-term exposure at 500 °C the reaction diffusion between aluminum and chromium occurs resulting in Al13Cr2 intermetallic formation and compacts swelling.