Stress and temperature change creep deformation in polycrystalline and polysynthetically twinned Ti-47Al-2Nb-2Cr

Book · Sun Dec 31 04:00:00 EST 1995

OSTI ID:225154

Bieler, T R; Seo, D Y; Beals, R S; Wu, C H; Choi, S L ^[1]

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1. Michigan State Univ., East Lansing, MI (United States). Dept. of Materials Science and Mechanics

Stress change and temperature change creep tests were conducted on investment cast and HIPed near-{gamma} Ti-47Al-2Nb-2Cr alloy (in the duplex microstructure), and on polysynthetically twinned (PST) crystals prepared from the same alloy. Initial results of shear-compression creep on the PST crystal and polycrystals are compared with data from tensile creep tests. Specimens were deformed at 760--808 C (1,400--1,480 F) at strain rates near 10{sup {minus}7} s{sup {minus}1}. The PST crystal was cut so that {l_brace}111{r_brace} lamellar planes were parallel to the 45{degree} axis in a compression-shear fixture and with {l_angle}110{r_angle} directions parallel to the principle resolved shear stress. Both specimens exhibited normal transients. The PST crystal exhibited an activation energy of about 150 kJ/mol and a stress exponent of n{approx}5, with are different from values obtained from the polycrystal deformed under similar conditions (260 kJ/mol, n{approx}3). These data are discussed in terms of current understanding of creep deformation in the literature.

• OSTI ID: 225154
• Report Number(s): CONF-950201--; ISBN 0-87339-304-X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ACTIVATION ENERGY
ALUMINIUM ALLOYS
CASTING
CHROMIUM ALLOYS
CREEP
EXPERIMENTAL DATA
HEAT TREATMENTS
HOT PRESSING
INTERMETALLIC COMPOUNDS
LAMELLAE
MONOCRYSTALS
NIOBIUM ALLOYS
ORIENTATION
SAMPLE PREPARATION
SLIP
STRAIN RATE
STRESSES
TEMPERATURE DEPENDENCE
TITANIUM ALLOYS
TWINNING
X-RAY DIFFRACTION