Advanced intermetallic γ-TiAl based alloys with improved microstructural stability during creep. Issue 1760 (2nd January 2015)

• Record Type: Journal Article
• Authors: Baker, I.; Heilmaier, M.; Kishida, K.; Mills, M.; Miura, S.; Kastenhuber, M.; Rashkova, B.; Clemens, H.; Mayer, S.
• Is Part Of: MRS proceedings. Issue 1760(2015)
• Publication Date: 2015-01-02
• Subjects: Electrical engineering -- Congresses; Physics -- Congresses; Materials -- Research -- Congresses; Materials science -- Congresses; 620.11
• DOI: 10.1557/opl.2014.968
• Languages: English
• ISSNs: 0272-9172

Abstract

<abstract abstract-type="normal"> <title>ABSTRACT</title> <p>Ensuring microstructural stability under technical relevant conditions is a determining criterion for the development of innovative high-temperature materials. In this work, the influ-ence of C and Si on the microstructural stability during creep exposure was investigated for a β-solidifying γ-TiAl based alloy with a nominal composition of Ti-43.5Al-4Nb-1Mo-0.1B (in at.%), named TNM. With a two-step heat treatment a microstructure consisting of fine lamellar α2/γ-colonies, surrounded by βo-phase and areas of discontinuous precipitation, starting from the boundaries of the lamellar colonies, was adjusted. Creep tests were carried out to examine the potential of C and Si to prevent microstructural instability during creep and hence improving the creep properties. At 815 °C the discontinuous precipitation process of the TNM alloy continues during ensuing creep testing leading to a reduced creep resistance. In comparison, the minimum creep rate of the TNM-0.3C-0.3Si alloy was significantly decreased caused by the lower βo-phase content and average lamellar spacing within the α2/γ-colonies, the precipitation of p-Ti3AlC carbides and the retarded kinetics of discontinuous precipitation.</p> </abstract>