phase 2 were hot isostatic pressed (HIP) prior to the T7 treat- ment in order to remove any porosity. The HIPing param- eters were 1,000 bar - 485C (905F) - 2 hrs.


T7 treatment: Differential scanning calorimetry (DSC) mea- surements were made on the Mg-free and Mg-containing variants to determine the incipient melting temperatures. It was concluded that the Mg-free variants could be safely so-


lutionized at 515C (959F), as could those with up to 0.19% Mg at 505C (941F). Quench was in 20C water. The aging parameters were 220C (428F) – 5 hrs. for the Mg-less and 210C (410F) – 4 hrs for the Mg-containing alloys in phase 1, and 200C (392F) – 5 hrs. in phases 2 to 4.


All samples destined to the 250C (482F) and 300C (572F) tensile tests and 300C (572F) creep tests were preheated 100


Table 1. The Four Experimental Phases of the Work


International Journal of Metalcasting/Summer 2011


19


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