In situ synchrotron radiation measurements of orthorhombic phase formation in an advanced TiAl alloy with modulated microstructure. Issue 1760 (2nd February 2015)

• Record Type: Journal Article
• Authors: Baker, I.; Heilmaier, M.; Kishida, K.; Mills, M.; Miura, S.; Rackel, M.; Stark, A.; Gabrisch, H.; Schimansky, F.-P.; Schell, N.; Schreyer, A.; Pyczak, F.
• Is Part Of: MRS proceedings. Issue 1760(2015)
• Publication Date: 2015-02-02
• Subjects: Electrical engineering -- Congresses; Physics -- Congresses; Materials -- Research -- Congresses; Materials science -- Congresses; 620.11
• DOI: 10.1557/opl.2015.31
• Languages: English
• ISSNs: 0272-9172

Abstract

<abstract abstract-type="normal"> <title>ABSTRACT</title> <p>New low aluminium high niobium TiAl alloys exhibit a nano scale modulated microstructure consisting of lamellae with a tweed substructure. These tweed like appearing lamellae are a modulated arrangement of at least two phases. One constituent of the crystallographic modulation in the lamellae is an orthorhombic phase, which is closely related to both the hexagonal α₂-Ti₃Al phase and the cubic B2 ordered β_o-TiAl phase.</p> <p>In this study the nature and formation of this orthorhombic phase has been investigated by high-energy X-ray diffraction.</p> <p>Measurements have shown that the newly formed orthorhombic phase is structurally comparable to the O phase (Ti₂AlNb). It forms in the temperature range of 550 °C to 670 °C from the α₂ phase by small atomic displacements and chemical reordering. The <italic>in situ</italic> experiments yielded information about the thermal stability of the orthorhombic phase. After dissolving at temperatures above 700 °C the phase can be re-precipitated by annealing within the temperature range of formation.</p> </abstract>