Metal treatment – Stock – Titanium – zirconium – or hafnium base
Patent
1996-03-26
2000-04-18
Ip, Sikyin
Metal treatment
Stock
Titanium, zirconium, or hafnium base
420418, C22C 1400
Patent
active
060510846
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
First, this invention relates to TiAl intermetallic compound-based alloys having excellent plastic workability and good resistance to oxidation at high temperatures and hence suitable for use in power-generating gas turbines, aircraft engines and the like, as well as a method for preparing the same.
Secondly, this invention relates to TiAl intermetallic compound-based alloys having high strength and good resistance to oxidation at high temperatures and hence suitable for use in power-generating gas turbines, aircraft engines and the like, as well as a method for preparing the same.
Thirdly, this invention relates to TiAl intermetallic compound-based alloys having high strength, good creep resistance and good oxidation resistance and hence suitable for use in power-generating gas turbines, aircraft engines and the like.
2. Background Art
(1) Background art concerning the first class of TiAl intermetallic compound-based alloys in accordance with the present invention and the method for preparing the same
Alloys comprising the intermetallic compound TiAl as the primary phase have favorable characteristics in that they are lighter in weight and higher in strength than conventional Ti alloys and in that their oxidation resistance is good at temperatures up to about 700.degree. C. Accordingly, it has been expected that they may be applicable to parts used in a high-temperature environment, such as turbine blades and turbine rotors. The aforesaid parts are of a complicated shape having three-dimensional curved surfaces, and one technique for creating such a product shape involves subjecting a material to plastic working (e.g., forging) using a die of the same profile.
TiAl intermetallic compound-based alloys are hard-to-work materials, and they must be heated to 1100.degree. C. or above in order to work them plastically to product shapes without developing defects such as cracks and cavities. However, dies which can be used at 1100.degree. C. or above on an industrial production level are not available in the present situation. Thus, their plastic working is difficult as a matter of fact and has not been put to practical use until now.
The composition of the TiAl intermetallic compound-based alloys which have hitherto been studied most closely is one having a slightly substoichiometric Al concentration of about 48 atomic percent and containing about 2 to 5 atomic percent of additional components, such as V, Mn, Cr and Nb, that may be used alone or in combination. The reason why the plastic workability of alloys of the aforesaid composition is insufficient is considered to be as follows:
In this composition, the generated phases are the TiAl phase (the L1.sub.0 crystal structure; hereinafter referred to as the .gamma. phase) and the Ti.sub.3 Al phase (the D0.sub.22 crystal structure; hereinafter referred to as the .alpha.2 phase) without regard to heat-treating conditions. Although its metallographic structure may vary slightly according to the heat-treating conditions, it is composed chiefly of coarse .gamma. phase and a similarly coarse lamellar structure (i.e., a structure comprising alternate layers of the .gamma. and .alpha.2 phases). The .gamma. and .alpha.2 phases are both intermetallic compound phases and do not have sufficient plastic ductility even in a high-temperature region. Moreover, the lamellar structure is a highly anisotropic structure and, when the applied deformation stress is perpendicular to the direction of the lamellae, its deformation resistance is so high that little deformation is caused. Furthermore, since each crystal grain is large, boundary sliding and the like seldom occur.
Because of the above-described factors associated with material characteristics, TiAl intermetallic compound-based alloys of the prior art composition fail to sufficient plastic workability at 1100.degree. C. or below. If it is tried to work them at 1100.degree. C. or below, the material tends to develop defects such as cracks and cavities. Moreover, owing to the high deformation r
REFERENCES:
patent: 5089225 (1992-02-01), Huang
patent: 5213635 (1993-05-01), Huang
patent: 5232661 (1993-08-01), Matsuo et al.
patent: 5264051 (1993-11-01), Huang
patent: 5284620 (1994-02-01), Larsen
patent: 5370839 (1994-12-01), Masahashi et al.
patent: 5417781 (1995-05-01), McQuay et al.
patent: 5431754 (1995-07-01), Fujiwara et al.
patent: 5558729 (1996-09-01), Kim et al.
Ip Sikyin
Mitsubishi Jukogyo Kabushiki Kaisha
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