In-Situ X-ray Diffraction Analysis of Solution Treatment under High Pressure and Extra Strengthening of Al-11.5 mass%Cu Alloy by Aging Treatment

This study applied solution treatment under high pressures as 2 and 6 GPa to an Al-11.5 mass%Cu alloy for increasing the solubility limit of Cu atoms. In-situ high-energy X-ray diffraction (XRD) analysis using a facility at SPring-8 in JASRI (Japan Synchrotron Radiation Research Institute) revealed dissolution behavior of θ-Al2Cu phase during the solution treatment. After the solution treatment under 6 GPa, all the Cu atoms in 11.5 mass% were dissolved in the Al matrix, almost twice as much as the solubility limit under ambient pressure, resulting in the increased Vickers microhardness to 148 HV. Further increase in Vickers microhardness to 206 HV was obtained after aging at 190°C, and the aging behavior was also examined by the in-situ high-energy XRD analysis. In this study, the effect of ultrafine-grained structure produced by severe plastic deformation through high-pressure sliding method was also elucidated.