New investigation of phase equilibria in the system Al-Cu-Si.

ABSTRACT: The phase equilibria and invariant reactions in the system Al-Cu-Si were investigated by a combination of optical microscopy, powder X-ray diffraction (XRD), differential thermal analysis (DTA) and electron probe micro analysis (EPMA). Isothermal phase equilibria were investigated within two isothermal sections. The isothermal section at 500 °C covers the whole ternary composition range and largely confirms the findings of previous phase diagram investigations. The isothermal section at 700 °C describes phase equilibria only in the complex Cu-rich part of the phase diagram. A new ternary compound ? was found in the region between (Al,Cu)-?(1) and (Cu,Si)-? and its solubility range was determined. The solubility of Al in ?-CuSi was found to be extremely high at 700 °C. In contrast, no ternary solubility in the ?-phase of Cu-Al was found, although this phase is supposed to form a complete solid solution according to previous phase diagram assessments. Two isopleths, at 10 and 40 at.% Si, were investigated by means of DTA and a partial ternary reaction scheme (Scheil diagram) was constructed, based on the current work and the latest findings in the binary systems Al-Cu and Cu-Si. The current study shows that the high temperature equilibria in the Cu-rich corner are still poorly understood and additional studies in this area would be favorable.

SUBMITTER: Ponweiser N 

PROVIDER: S-EPMC3223527 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature