Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

This work studied the precipitation characteristics of AlSi10Mg0.3Mn alloy produced by high-pressure vacuum die-casting in T5 and T6 conditions using transmission electron microscopy, differential scanning calorimetry and both electrical conductivity and microhardness measurements. Two different T6 tempers were used, involving partial solutionizing at 460 °C for 1 h and full solutionizing at 500 °C for 1 h, and were designated as T6P and T6F, respectively. The aging treatment was conducted at 185 °C for 4 h in all temper conditions. The results showed that conducting solution treatments resulted in the formation of α-Al(MnFe)Si dispersoids. In addition, Mg–Si rich precipitates formed and remained undissolved after partial solutionizing. The highest supersaturation of the α-Al was achieved in the as-fabricated (F) condition by the HPVDC process. The supersaturation degree decreased in both partial and full solutionizing conditions. TEM observations revealed different precipitation characteristics for T5, T6P and T6F tempers. β” precipitates just started to form in the T5 condition, whereas both β” and β’ precipitates completed their precipitation to different extents in the T6P and T6F conditions, resulting in different strengthening effects. The T6F temper yielded the highest microhardness followed by the T5 and T6P tempers.