Effect of Sn on the Dehydrogenation Process of TiH2 in Al Foams

The study of the dehydrogenation process of TiH2 in aluminum foams produced by the powder metallurgy technique is essential to understanding its foaming behavior. Tin was added to the Al foam to modify the dehydrogenation process and stabilize the foam. A gradual decomposition and more retention of hydrogen gas can be achieved with Sn addition resulting in a gradual and larger expansion of the foam

INTERNAL FRICTION PEAKS IN A COMMERCIAL DURALLOY

Un alliage commercial Al 2024 de la famille des"dur-aluminiums" Al - 4,5% pd Cu -1,5% pd Mg - 0,6% pd Mn - < 1% pd d'impurités (Fe, Si) a été étudié par frottement intérieur à basses fréquences. L'état commercial "C" a été soumis soit à des traitemens thermiques ou thermo-mécaniques, soit à l'irradiation neutronique ou électronique, afin de préparer les différents échantillons. L'état "C" présente deux sortes de pics : près de la température ambiante à 1Hz, des pics d'écrouissage à froid et à 244°C (24Hz), un pic d'interaction des dislocations avec précipités avec une énergie d'activation de 0,94 eV. La seule présence des dislocations ou des précipités ne donne pas ce dernier pic. À partir de 200°C le fond de hautes températures est important suivant une loi exponentielle similaire à celle d'autres alliages d'Aluminium. L'état en solution solide sursaturée "SSS" présente un double pic de Zener qui peut être considéré comme l'apport de seulement deux solutés : le Cu et le Si. Le fond des hautes températures observé est moins important que dans l'état "C". De la comparaison des fonds de tous les échantillons on interprète qu'ils sont dus au mouvement des dislocations.The commercial duralloy Al 2024 of composition Al-4.5 wt% Cu-1.5 wt% Mg-0.6 wt% Mn - < 1 wt% impurities (Si, Fe) was studied by internal friction at low frequencies. The commercial state "C" was submitted to different thermal and/or mechanical treatments and neutron or electron irradiations to prepare the various samples. The "C" state presented two kinds of peaks : some cold work peaks at 1 Hz below and near room temperature and a precipitates-dislocations interaction peak at 244°C (24Hz) with activation energy of 0.94 eV. The presence of dislocations of precipitates alone in the sample leads to the absence of appreciable peaks. At about 200°C the increase of the high temperature background follows an exponential law similar to other Al alloys. The supersaturated solid solution "SSS" state presented a double Zener type peak that can be considered as a contribution of both solutes : Cu and Si. The high temperature background is aloso present, but a little lower than in the "C" state. By comparing the backgrounds of all the samples we arrive at the conclusion that its origin is dislocation motion

Processing and pore growth mechanisms in aluminum gasarites produced by thermal decomposition

Gasarites are a subclass of metallic foams that have a cylindrical pore morphology created by directional solidification of metals saturated with a gas. Thermal decomposition is an alternative process in which the soluble gas is delivered by decomposition of a particulate gas source. Aluminum gasarites formed through decomposition of titanium and zirconium hydrides were studied to both replicate the results of a previous study and discern pore-formation mechanisms. Replication of the previous study was not achieved, and additional processing enhancements were required to produce gasarite pore morphologies. For the first time, zirconium hydride was utilized to produce gasarites, with porosity levels and pore sizes lower than that from titanium hydride. Maximum average porosity levels of 10 and 6 pct were observed for titanium hydride and zirconium hydride, respectively. Pore-formation mechanisms in aluminum gasarite foams created via thermal decomposition of titanium and zirconium hydrides were evaluated through metallographic analysis and scanning electron microscopy. Definitive evidence of gas–metal eutectic pore growth was not found, but pore morphological characteristics and chemical analysis of particulate at pore surfaces support direct gas evolution from the hydride particles as a contributor to pore formation and growth