Pd. Nicolaou et Sl. Semiatin, HIGH-TEMPERATURE DEFORMATION AND FAILURE OF AN ORTHORHOMBIC TITANIUM ALUMINIDE SHEET MATERIAL, Metallurgical and materials transactions. A, Physical metallurgy andmaterials science, 27(11), 1996, pp. 3675-3681
The high-temperature deformation and failure behavior of an orthorhomb
ic titanium aluminide sheet alloy (fabricated by diffusion bonding of
six thin foils) was established by conducting uniaxial tension and pla
ne-strain compression tests at 980 degrees C and strain rates between
10(-4) and 10(-2) s(-1). The stress-strain response was characterized
by a peak stress at low strains followed by moderate flow softening. V
alues of the strain-rate sensitivity index (m) were between 0.10 and 0
.32, and the plastic anisotropy parameter (R) was of the order of 0.6
to 1.0. Cavity nucleation and growth were observed during tensile defo
rmation at strain rates of 10(-3) s(-1) and higher. However, the combi
ned effects of low m, low cavity growth rate eta, and flow softening w
ere deduced to be the source of failure controlled by necking and flow
localization rather than cavitation-induced fracture prior to necking
.