Paper Title:
The Effects of Heat Treatments and Tungsten Additions on Microstructures and Tensile Properties of Powder Metallurgy Ti-48Al-2Nb-2Cr
  Abstract

The microstructures and tensile properties of a fully lamellar Ti-48Al-2Cr-2Nb, and two tungsten-modified versions, Ti-48Al-2Cr-2Nb-0.5W and Ti-48Al-2Cr-2Nb-1.0W (atomic percent) are investigated. Gas atomized powders are consolidated by hot isostatic pressing followed by solution treatment and aging. The microstructures are characterized by optical, scanning electron, and transmission electron microscopy and mechanical properties are characterized by room temperature tensile testing. The solution heat treatment, combined with controlled cooling, generates relatively fine, fully lamellar grains. Tungsten reduces the propensity for martensitic gamma formation during cooling, and slows down lamellar coarsening as well as the formation of equiaxed gamma phase during aging. The aging treatment stabilizes the microstructure and, in the tungsten-modified alloys, causes beta phase precipitation at lamellar interfaces and grain boundaries. Both aging and tungsten additions increase the alloy strength and reduce ductility. The fracture morphologies of the alloys are similar and exhibit mixed-mode fracture consisting of inter- and intra-granular cracking, as well as inter-lamellar cracking.

  Info
Periodical
Materials Science Forum (Volumes 638-642)
Main Theme
Edited by
T. Chandra, N. Wanderka, W. Reimers , M. Ionescu
Pages
1406-1411
DOI
10.4028/www.scientific.net/MSF.638-642.1406
Citation
D. Y. Seo, S. Bulmer, H. Saari, P. Au, "The Effects of Heat Treatments and Tungsten Additions on Microstructures and Tensile Properties of Powder Metallurgy Ti-48Al-2Nb-2Cr", Materials Science Forum, Vols. 638-642, pp. 1406-1411, 2010
Online since
January 2010
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