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Thermal Analysis of the Impact of RT Storage Time on the Strengthening of an Al-Mg-Si Alloy

“…A total of seven enthalpic signals (numbered I-VII), four of which are exothermic, are identified in the DSC spectrum, obtained by heating at 15˚C·min −1 of the as quenched sample (Figure 1). According to several previous works [4][5][6]8,9,[12][13][14], these calorimetric events can be correlated to the precipitation process as follows:  The first exothermic peak centring around 100˚C (effect I) is caused by GP zones and/or clusters formation;  The small endothermic signal with a minimum at approximately 220˚C (effect II) is produced by the dissolution of the clusters and/or GP zones which have formed below 150˚C;  The major exothermic peak which follows right after and lasts until 300˚C (effect III) is clearly linked with the precipitation of the principal hardening phase ".…”

“…Since the discovery of age hardening of Al-Mg-Si alloys some 90 years ago a significant amount of work on characterising and understanding the precipitation behaviour of these alloys has been carried out [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Factors such as low degree of activation during irradiation, high corrosion resistance in vapour-water media, high weldability, medium strength, high extrudability have supported the usage of these alloys as structural materials in the industry of nuclear research reactors [1].…”

“…The extent of these structural changes depends on the applied temperature, the time the material is exposed to temperature, and how fast it is cooled to room temperature. Despite the considerable literature devoted to this subject [2][3][4][5][6][7][8][9][10][11][12][13][14][15], these structural changes have not been fully understood. However, it was generally accepted that the precipitation behaviour follows the scheme: supersaturated solid solution (S.S.S.)…”

Effect of hot extrusion on mechanical properties and microstructure of near eutectic Al–12.0%Si–0.2%Mg alloy

“…The general precipitation sequence of Mg 2 Si phase in Al-Mg-Si system is well known as super-saturated solid solution-GP zone-␤ -␤ -␤ (Mg 2 Si), of which ␤ (Mg 5 Si 6 ) needles, with diameter of several nanometers and length of tens to hundreds of nanometers, are the most effective strengthening meta-stable phases of ␤ (Mg 2 Si), following a little coarser ␤ (Mg 9 Si 5 ) particles [2,[8][9][10][11][12]. But improvement of strength is usually achieved at the expense of decrease in ductility.…”

Effect of heat treatment on the precipitation in Al–1at.% Mg–xat.% Si (x=0.6, 1.0 and 1.6) alloys

“…For balanced alloys, the decomposition of the SSSS obtained as a result of aging at intermediate temperatures is generally believed to be as follows [3]:…”