Table of Contents
Textures and Microstructures
Volume 13, Issue 1, Pages 1-14
http://dx.doi.org/10.1155/TSM.13.1

Directionally Solidified Materials: Nickel-base Superalloys for Gas Turbines

Laboratoire de Science et Génie des Matériaux Métalliques, Ecole des Mines, Nancy cédex 54042, France

Received 20 December 1989

Copyright © 1990 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

From the first forged turbine blades made of iron base alloys to the present nickel base single-grain turbine blades and vanes manufactured by directional solidification, an enormous amount of research has been directed to attaining the hottest possible combustion chamber temperatures in jet engines. Temperature has been increased by about 15 K each year for the last two decades, improving the thermodynamic efficiency of the engines. The more recent developments concern the manufacturing of single-grain parts made of nickel base superalloys with large amount of the γ′ hardening phase.

This paper first presents the directional solidification process used to produce single-grain parts, the formation of as-cast microstructures and the defects that can arise during solidification. In the second part the thermal treatments that are applied to the nickel base superalloys in order to enhance their mechanical properties are detailed. The effect of crystallographic orientation and of the γ/γ′ microstructure on the mechanical properties is briefly presented, as well as the. microstructural changes that can possibly arise during service.