Temperature Effects on the Tensile Properties of Precipitation-Hardened Al-Mg-Cu-Si Alloys
Because the mechanical performance of precipitation-hardened alloys can be significantly altered with temperature changes, understanding and predicting the effects of temperatures on various mechanical properties for these alloys are important. In the present work, an analytical model has been developed to predict the elastic modulus, the yield stress, the failure stress, and the failure strain taking into consideration the effect of temperatures for precipitation-hardenable Al-Mg-Cu-Si Alloys (Al-A319 alloys). In addition, other important mechanical properties of Al-A319 alloys including the strain hardening exponent, the strength coefficient, and the ductility parameter can be estimated using the current model. It is demonstrated that the prediction results based on the proposed model are in good agreement with those obtained experimentally in Al-A319 alloys in the as-cast condition and after W and T7 heat treatments.
Optimizing the tensile properties of Al–Si–Cu–Mg 319-type alloys: Role of solution heat treatment
Abstract The work presented in this study was carried out on Al–Si–Cu–Mg 319-type alloys to investigate the role of solution heat treatment on the dissolution of copper-containing phases (CuAl 2 and Al 5 Mg 8 Cu 2 Si 6 ) in 319-type alloys containing different Mg levels, to determine the optimum solution heat treatment with respect to the occurrence of incipient melting, in relation to the alloy properties. Two series of alloys were investigated: a series of experimental Al–7 wt% Si–3.5 wt% Cu alloys containing 0, 0.3, and 0.6 wt% Mg levels. The second series was based on industrial B319 alloy. The present results show that optimum combination of Mg and Sr in this study is 0.3 wt% Mg with 150 ppm Sr, viz. for the Y4S alloy. The corresponding tensile properties in the as-cast condition are 260 MPa (YS), 326 MPa (UTS), and 1.50% (%El), compared to 145 MPa (YS), 232 MPa (UTS), and 2.4% (%El) for the base alloy with no Mg. At 520 °C solution temperature, incipient melting of Al 5 Mg 8 Cu 2 Si 6 phase and undissolved block-like Al 2 Cu takes place. At the same time, the Si particles become rounder. Therefore, the tensile properties of Mg-containing alloys are controlled by the combined effects of dissolution of Al 2 Cu, incipient melting of Al 5 Mg 8 Cu 2 Si 6 phase and Al 2 Cu phase, as well as the Si particle characteristics.
The problems of interprofessional healthcare practice in hospitals.
This article outlines the problems of interprofessional practice in the hospital setting. It examines the difficulties associated with competing ideologies and aims, inequalities in power relations, communication and role confusion and overlap. Within the hospital setting such problems often arise although the roots of the problem may go unacknowledged. The ways in which the problems occur in the hospital setting are considered, as is the underlying cause of such problems. Case studies will be used to analyse how the problems arise and ways in which they might be addressed.