Quantification of volume fraction of precipitates in an aged Al-1.0 mass%Mg2Si alloy

Abstract

An Al-1.0 mass%Mg 2 Si alloy was aged at 473 K for 36ks. Using the same sample, resistivity (p) measurements, tensile tests and TEM observations were carried out. The volume fraction (V fρ ) of precipitates was estimated from the decrement in resistivity due to aging. Length (λ), diameter (d) and number density (Np) per unit volume of the needle-shaped precipitates were measured on TEM micrographs. Perhaps because of initiation of overaging in the present aging condition, λ and Np showed a wide scatter and differed significantly in two equivalent samples, independently heat treated and tested. However, proof stress and V fρ in the two runs well coincided with each other and the volume fraction estimated from TEM micrographs (V fTEM ) matched within a factor of 2 for the two runs.