A quantitative study by transmission electron microscopy of nanoscale precipitates in Al-Mg-Si alloys

We report a quantitative study of hardening precipitates carried out by mea ns of transmission electron microscopy (TEM). Several TEM techniques are co upled to draw quantitative information without the help of a hypothesis on the precipitate structure and composition. The method is illustrated by an investigation of hardening precipitates in an Al-Mg-Si alloy 6056 (T6 tempe r). This microstructure consists of two precipitate families: lath and rod. The TEM study leads for the rod precipitate to a volume fraction of 1.3 +/ - 0.1% and a number density of 8.6 +/- 0.4 x 10(16) cm(3) We also obtained the rod size distribution and a mean rod diameter of 2.86 nm. The lath prec ipitate volume fraction and density are also estimated but with less precis ion. The present results are discussed in comparison with a previous small- angle scattering study carried out on the same material.