A THERMODYNAMIC APPROACH TO THE POSSIBILITIES FOR REPLACING EXPENSIVE ELEMENTS IN HIGH TEMPERATURE ALLOYS
The application of thermodynamics to exploring the potential for replacement of expensive elements in high temperature alloys is examined. Seven aspects of materials affecting performance are considered: solidus temperature prediction, avoidance of sigma phase formation, development of desirable phases, tramp element control, corrosion in gaseous environments, corrosion in molten salts and vaporization. The value of the thermodynamic approach is demonstrated for each of these aspects, including, for example, the consequences of reducing the chromium content of alloys and its replacement by aluminium or silicon. Phase diagrams for the following systems are provided: Al- Cr-Co-Ni, Al-Cr-Ni, Co-Cr-Ni, Al-Co-Cr-Ni, Cr-Fe-Ni, Cr-Fe-Si, Cr-Fe-Ni-Si, Cr-Fe-Ni-Ti. Also included are phase equilibria diagrams relating to tramp element control in multicomponent low alloy steels and diagrams illustrating the interaction of Al, Ca, Cr, Fe and Ni with combustion atmospheres carrying sulphur and chlorine impurities. It is concluded that there is an excellent case for the further development and use of computer data banks incorporating calculation software as well as data. The data base should be broad enough to include the alloying elements, their corrosion products, and the species present in corroding environments, including both gases and molten salts.
Bibliographic Reference: EUR 9564 EN (1985) FS, 146 P., BFR 500, EUROFFICE, LUXEMBOURG, POB 1003
Availability: Can be ordered online
Record Number: 1989123043500 / Last updated on: 1987-01-01
Available languages: en