Effect of Superplastic Processing on Room Temperature Ductility of Gamma Titanium Aluminide

The microstructure and creep properties of two powder metallurgy (PM) ‘beta gamma’ titanium aluminide alloys are presented. Alloy powders with nominal compositions of TiAl-4Nb-3Mn (G1) and TiAl-2Nb-2Mo (G2) were produced by gas atomization and consolidated by a two-step hot isostatic pressing (HIP) process (1250 °C/200 MPa/1 hour + 1100 °C/200 MPa/3 hours + slow cooling to room temperature). After HIP, the materials were given a step cooled heat treatment (SCHT) of 40 min at 1400 °C, furnace cooling to 1280 °C, and air cooling to room temperature. Selected specimens were aged at 900 °C for 6 or 24 hours. The SCHT yielded similar fully lamellar microstructures for both alloys, with a lamellar spacing of 0.04 m, but with different grain sizes averaging 80 m (G1) and 40 m (G2). The aging treatments generated  precipitates along lamellar colony boundaries in both alloys, but along lamellar interfaces only in alloy G2. Constant load tensile creep tests were performed at 760 °C and 276 MPa. Alloy G2 exhibited superior creep performance compared to alloy G1, due to the quantity and size of  precipitate particles at the lamellar interfaces.

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Cyclic deformation mechanisms in a gamma titanium aluminide alloy at room temperature

Scripta Materialia ◽

10.1016/j.scriptamat.2004.09.022 ◽

2005 ◽

Vol 52 (2) ◽

pp. 107-111 ◽

Cited By ~ 17

Author(s):

A.L. Gloanec ◽

G. Henaff ◽

M. Jouiad ◽

D. Bertheau ◽

P. Belaygue ◽

...

Keyword(s):

Cyclic Deformation ◽

Titanium Aluminide ◽

Room Temperature ◽

Deformation Mechanisms ◽

Gamma Titanium Aluminide ◽

Gamma Titanium ◽

Titanium Aluminide Alloy

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Limitations of an Indentation Model for Grinding Gamma Titanium Aluminide

Dynamic Systems and Control ◽

10.1115/imece2002-32038 ◽

2002 ◽

Author(s):

H. Ali Razavi ◽

Steven Danyluk ◽

Thomas R. Kurfess

Keyword(s):

Force Control ◽

Titanium Aluminide ◽

Normal Force ◽

Removal Rate ◽

Cubic Boron Nitride ◽

Normal Component ◽

Grinding Force ◽

Cutting Depth ◽

Gamma Titanium Aluminide ◽

Gamma Titanium

This paper explores the limitations of a previously reported indentation model that correlated the depth of plastic deformation and the normal component of the grinding force. The indentation model for grinding is studied using force control grinding of gamma titanium aluminide (TiAl-γ). Reciprocating surface grinding is carried out for a range of normal force 15–90 N, a cutting depth of 20–40 μm and removal rate of 1–9 mm3/sec using diamond, cubic boron nitride (CBN) and aluminum oxide (Al2O3) abrasives. The experimental data show that the indentation model for grinding is a valid approximation when the normal component of grinding force exceeds some value that is abrasive dependent.

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The Dependence of Tensile Ductility on Investment Casting Parameters in Gamma Titanium Aluminides

MRS Proceedings ◽

10.1557/proc-552-kk2.1.1 ◽

1998 ◽

Vol 552 ◽

Author(s):

R. Raban ◽

L. L. ◽

T. M.

Keyword(s):

Titanium Aluminide ◽

Titanium Aluminides ◽

Tensile Ductility ◽

Gamma Titanium Aluminide ◽

Cooling Rates ◽

Gamma Titanium ◽

Investment Cast ◽

Thermal Data ◽

Titanium Aluminide Alloys ◽

Simulation Package

ABSTRACTPlates of three gamma titanium aluminide alloys have been investment cast with a wide variety of casting conditions designed to influence cooling rates. These alloys include Ti-48Al-2Cr-2Nb, Ti- 47Al-2Cr-2Nb+0.5at%B and Ti-45Al-2Cr-2Nb+0.9at%B. Cooling rates have been estimated with the use of thermal data from casting experiments, along with the UES ProCAST simulation package. Variations in cooling rate significantly influenced the microstructure and tensile properties of all three alloys.

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