DSC-measurements show in a simple and convincing manner that the precipitation of the metastableS′-phase in an Al-2.1% Cu-1.3% Mg alloy is enhanced in the presence of lattice defects (dislocation loops, helices, dislocations), but is little influenced by pre-existing GPB-zones.
Authors:A. M. Zahra, C. Y. Zahra, R. Castanet, G. Jaroma-Weiland, and G. Neuer
The thermophysical properties of solid aluminium, magnesium and titanium alloys are extracted from literature and new measurements performed within a European concerted action (CONST 507D). In Marseille, heat capacity values for binary and ternary aluminium alloys as well as for industrial aluminium and titanium alloys are assessed between 20° and 600°C from DSC and heat content measurements using a drop method; enthalpies accompanying the precipitation and dissolution of metastable and stable phases are determined. All values are stored into the databank THERSYST together with detailed description of the materials and of the experimental conditions. Special modules enable the data selection, representation and manipulation according to the user's criteria.
Authors:A. M. Zahra, C. Y. Zahra, M. Ganteaume, S. Rossignol, B. Tanguy, J. J. Videau, and J. Portier
The glass forming ranges in the TeO2-AgO0.5 and TeO2-AgO0.5-AgI systems have been assessed for two cooling rates; results based on heat capacity and electrical conductivity measurements as well as derived from infrared spectroscopy are presented. The ternary glasses are excellent conductors due to the presence of Ag+ ions mainly supplied by AgI. The decrease in ΔCP with increasing AgI-content suggests the presence of AgI microdomains which are finely distributed and do not contribute to the configurational heat capacity change. Fast motion of Ag+ ions (low activation energy) occurs in the glassy matrix which shows slow structural relaxation (high activation barrier).