Terryl A. Wallace
Langley Research Center
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Featured researches published by Terryl A. Wallace.
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing | 1998
William D Brewer; R. Keith Bird; Terryl A. Wallace
Commercially available titanium alloys as well as emerging titanium alloys with limited or no production experience are being considered for a variety of applications to high speed commercial aircraft structures. A number of government and industry programs are underway to improve the performance of promising alloys by chemistry and/or processing modifications and to identify appropriate alloys and processes for specific aircraft structural applications. This paper discusses some results to date of NASA sponsored research on the effects of heat treatment, service temperatures from −54 to +177°C, and selected processing on the mechanical properties of several candidate β and α-β titanium alloys. Included are β alloys Timetal 21S, LCB, Beta-C, Beta-CEZ and Ti-10-2–3 and α-β alloys Ti-62222, Ti-6242S, Timetal 550, Ti-62S, SP-700 and Corona-X. The emphasis is on strength and toughness properties of rolled sheet product and on the superplastic properties and processing of the materials.
Oxidation of Metals | 1992
Terryl A. Wallace; Ronald K. Clark; Karl E. Wiedemann; Sankara N. Sankaran
Static oxidation kinetics of Ti-25Al-10Nb-3V-1Mo (atomic percent) were investigated in air over the temperature range of 650–1000°C using thermogravimetric analysis. The oxidation kinetics were complex at all exposure temperatures and displayed up to two distinct stages of parabolic oxidation. Breakaway oxidation occurred after long exposure times at high temperatures. Oxidation products were determined using x-ray diffraction techniques, electron microprobe analysis, and energy dispersive x-ray analysis. Oxide scale morphology was examined using scanning electron microscopy of the surfaces and cross-sections of oxidation specimens. The oxides during the parabolic stages were compact and multilayered, consisting primarily of TiO2 doped with Nb, a top layer of Al2O3 and a thin bottom layer of TiN. The transition between the first and second parabolic stage is linked to the formation of a TiAl layer at the oxide-metal interface. Porosity also formed in the TiO2 layer during the second stage, causing degradation of the oxide and breakaway oxidation.
Oxidation of Metals | 1994
Terryl A. Wallace; Ronald K. Clark; Karl E. Wiedemann
The oxidation behavior of Ti−14Al−21Nb in air and in oxygen was determined over the temperature range 700 to 1000°C. Weight gains in both atmospheres were measured using thermogravimetric analysis. The resulting oxidation products were identified using X-ray diffraction, and oxide morphology was evaluated using electron microscopy and wavelength-dispersive X-ray analysis. Total weight gains in oxygen were up to four times higher than in air, and a higher percentage of the weight gain in oxygen was due to oxygen dissolution into the metal. Based on metallurgical examination of the oxidized specimens, it was concluded that the lower oxidation weight gains in air are due to the formation of a thin layer of TiN and TiAl at the oxide-metal interface which inhibits the diffusion of oxygen into the metal.
Journal of Spacecraft and Rockets | 2004
R. Keith Bird; Terryl A. Wallace; Sankara N. Sankaran
Archive | 1992
Terryl A. Wallace; Ronald K. Clark; Karl E. Wiedemann
Engineering Failure Analysis | 2010
John A. Newman; James M. Baughman; Terryl A. Wallace
Archive | 1990
Terryl A. Wallace; Ronald K. Clark; Sankara N. Sankaran; Karl E. Wiedemann
Archive | 2014
Patrick E. Leser; John A. Newman; Stephen W. Smith; William P. Leser; Russell A. Wincheski; Terryl A. Wallace; Edward H. Glaessgen; Robert S. Piascik
Archive | 2009
John A. Newman; James M. Baughman; Terryl A. Wallace
Oxidation of Metals | 1994
Terryl A. Wallace; Ronald K. Clark; Karl E. Wiedemann