The uniaxial hot tension behavior of sheet of anear-y titanium aluminide alloy (Ti-45.5Al-2Cr-2Nb) wasdetermined in the as-rolled condition (initial grain size ≈3 to 5#mu#m) and a rolled-and-heat treated (1175 deg C/4 hours)condition (initial grain size ≈10 to 12 #mu#m). Microstructureevolution, cavitation rates, and failure modes were establishedvia constant strain rate tests at 10~(-3) sec~(-1) and testtemperatures between 900 and 1200 deg C. After extensivedeformation, all specimens exhibited grain refinement at thelower test temperatures; at higher test temperatures, the as-rolledspecimens revealed grain growth and the heat treated samplesshowed grain refinement. For both initial microstructuralconditions, the failure mode was established as predominantlycavitation/fracture controlled. Cavity growth rates were greatestat lower temperatures and in the heat treated specimens with thecoarser initial grain size; the higher cavitation rates in the heattreated specimens led to total elongations only approximatelyone-half those of the as-rolled material. For both initialmicrostructural conditions, the optimum forming temperaturewas 1200 deg C. At this temperature, the maximum elongations,minimum cavitation rates, and lowest flow stresses were observed.
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