Quantification of precipitate fraction in Al–Si–Cu alloys

Quantification of precipitate fraction is difficult when the precipitates formed are of low volume fraction. A simple method is proposed in the present work to estimate the precipitate fraction of Al2Cu phase in Al–Si–Cu alloys based on X-ray diffraction analysis. The change in the lattice parameter of the matrix due to ageing, measured from X-ray diffraction profiles, is correlated to the fraction of Al2Cu phase formed during ageing. JMatPro, a software package for calculating the properties of metallic systems, is used to calculate the phase constitution and composition in the Al–Si–Cu alloys studied after different heat treatments. Factors that affect the lattice parameter of the matrix have been discussed and considered in the calculations.