Dependence on their Mn and Cr contents of the microstructures, melting range and high temperature creep behaviors of Cantor’s alloy and versions strengthened by MC carbides
Résumé
Decreasing Mn and increasing Cr in the cast Cantor’s alloys and their MC–strengthened versions induce significant improvements for their oxidation behaviors at high temperature [1]. But these changes in the chemical composition may have also consequences on the microstructures, the refractoriness and the high temperature mechanical properties. The aim of this work is first to perform differential thermal analyses (DTA) for specifying the temperatures of starts and stops of melting and solidification. Second, it is also to characterize the creep resistances of these alloys by the mean of 3 points flexural creep tests, carried out at several temperatures in the [1,000 – 1,200°C] range for several values of the induced maximal tensile stress varying ranging from 10 to 20 MPa. Clearly, the contents in Mn (the less refractory element in the Cantor’s composition) and in Cr (the most refractory one), have both an influence of the melting range of the three types of alloys: the carbide–free ones, the TaC– containing ones and the HfC–containing ones. Decreasing the Mn content and increasing the Cr one at the same time induce an increase in solidus temperature, with possible favorable consequence on the creep resistance. An increase in liquidus temperature can be also noted and this may influence the castability of the alloys. Concerning the creep resistance, no certain effect of these refractoriness differences was proven with the creep tests which were performed. This is much more the presence or not of TaC or HfC carbides which plays an important role for the creep resistance.
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