Journal ArticleDOI
Alloying mechanism of beta stabilizers in a TiAl alloy
TLDR
In this article, the effects of beta stabilizers such as Fe, Cr, V, and Nb on the microstructures and phase constituents of Ti52Al48-xM alloys were investigated.Abstract:
The effects of beta stabilizers such as Fe, Cr, V, and Nb on the microstructures and phase constituents of Ti52Al48-xM (x=0, 1.0, 2.0, 4.0, or 6.0 at. pct and M=Fe, Cr, V, and Nb) alloys were studied. The dependence of the tensile properties and creep resistance of TiAl on the alloying elements, especially the formation of B2 phase, was investigated. Fe is the strongest B2 stabilizer, Cr is second, V is an intermediate stabilizer, and Nb is the weakest stabilizer. The composition partitioning of Fe, Cr, V, and Nb in the γ phase is affected by the formation of B2 phase. The peaks of the tensile strengths and creep rupture life of Ti52Al48-xM generally occur at the maximum solid solution of these elements in the γ phase, which is just before the formation of B2 phase. Ti52Al48-0.5Fe shows an attractive elongation of 2.5 pct at room temperature, and the Ti52Al48-1V, Ti52Al48-Cr, and Ti52Al48-2Nb alloys have about 1.1 to 1.3 pct elongation at room temperature. The increase of tensile strengths and creep resistance with increasing Fe, Cr, V, and Nb contents is chiefly attributed to the solid-solution strengthening of these elements in the γ phase. The appearance of B2 phase deteriorates the creep resistance, room-temperature strengths, and ductility. With respect to the maximum solid-solution strengthening, an empirical equation of the Cr equivalent [Cr] is suggested as follows: [Cr]=Cr+Mn+3/5V+3/8Nb+3/2 (W+Mo)+3Fe=1.5 to 3.0. The solid-solution strengthening mechanism of Fe, Cr, V, and Nb at room temperature arises from the increase of the Ti 3s and Al 2s binding energies in Ti-Ti and Al-Al bonds, and the retention of the strength and creep resistance at elevated temperatures in Ti52Al48-xM is mainly attributed to the increase of the Ti 3s and Al 2s binding energies in Ti-Al bonds in γ phase. The decrease of the Ti 3p and Al 2p binding energies in Ti-Ti, Ti-Al, and Al-Al bonds benefits the ductility of TiAl.read more
Citations
More filters
Journal ArticleDOI
Design, Processing, Microstructure, Properties, and Applications of Advanced Intermetallic TiAl Alloys†
Helmut Clemens,Svea Mayer +1 more
TL;DR: In this article, a general survey of engineering γ-TiAl based alloys is given, but concentrates on β-solidifying alloys which show excellent hot-workability and balanced mechanical properties when subjected to adapted heat treatments.
Journal ArticleDOI
Microstructure evolution and mechanical properties of a novel beta γ-TiAl alloy
TL;DR: In this paper, a new beta gamma TiAl alloy was fabricated by ISM method, which consisted of fine lamellar colonies and mixtures of small γ and B2 grains around the colony boundaries.
Journal ArticleDOI
Phase fractions, transition and ordering temperatures in TiAl–Nb–Mo alloys: An in- and ex-situ study
Thomas Schmoelzer,Klaus-Dieter Liss,Gerald A. Zickler,Ian J. Watson,Laura M. Droessler,Wilfried Wallgram,Thomas Buslaps,Andrew J Studer,Helmut Clemens +8 more
TL;DR: In this paper, in-and ex-situ experiments were conducted on three alloys with different contents of β/β 0 stabilizing elements, and the course of phase fractions as a function of temperature as well as phase transition temperatures were determined by means of high-energy X-ray diffraction experiments.
Journal ArticleDOI
Phase transformation and decomposition mechanisms of the βo(ω) phase in cast high Nb containing TiAl alloy
TL;DR: In this paper, the interconversion mechanism between the ordered ω and β o phases and the decomposition process of the β o phase in the as-cast Ti-45Al-8.5Nb-0.2W−0.02Y (at%) alloy are studied.
Journal ArticleDOI
Hot deformation behavior and dynamic recrystallization of a β-solidifying TiAl alloy
TL;DR: In this paper, the deformation behavior and dynamic recrystallization of a β-solidifying TiAl alloy was investigated by means of isothermal compression tests in a temperature range of 1100 −1225 −C and strain rate range of 0.01 −0.05 −1.
References
More filters
Journal ArticleDOI
Ordered intermetallic alloys, part III: Gamma titanium aluminides
TL;DR: In this paper, an improved understanding of both fundamental and practical aspects of these aluminides, such as phase relations, microstructure evolution and control, processing, micro-structure-property relationships, and deformation and fracture processes, is presented.
Journal ArticleDOI
Microstructural evolution and mechanical properties of a forged gamma titanium aluminide alloy
TL;DR: A two-phase gamma titanium aluminide alloy, Ti-47Al-1Cr-1V-2.5Nb, was studied under forged and various subsequent heat treatment conditions, to investigate the microstructural evolution and the effect of microstructure on room temperature (RT) tensile properties and fracture toughness behavior as discussed by the authors.
Journal ArticleDOI
Synthesis, properties and applications of titanium aluminides
TL;DR: In this paper, the basic phase diagram and crystal structure of both the Ti3Al and TiAl phases are reviewed, followed by a consideration of chemistry-processing-microstructure-deformation/fracture-mechanical property relationships in monolithic material.
Journal ArticleDOI
The effects of Cr additions to binary TiAl-base alloys
Shyh-Chin Huang,Ernest L. Hall +1 more
TL;DR: In this paper, the effects of Cr additions to y-base alloys have been investigated, using bulk materials consolidated from rapid solidification-processed ribbons, and it was concluded that the ductilization effect of Cr in duplex alloys is partially due to the tendency of Cr to occupy Al lattice sites.