Omega phase formation in titanium and titanium alloys

Conference · Wed Jan 01 00:00:00 EST 1992

OSTI ID:5406462

Gray, III, G T; Morris, C E; Lawson, A C

Although the response of titanium alloys to dynamic loading is receiving increased attention in the literature (particularly in the area of shear-band formation), a more limited experimental database exists concerning the detailed structure/property relationships of titanium alloys subjected to shock loading. In this study, preliminary results concerning the influence of alloy chemistry on the property of omega-phase formation and its structure in three titanium alloys are presented. The influence of shock-wave deformation on the phase stability and substructure evolution of high-purity (low-interstitial) titanium, A-70 (3700 ppm oxygen) titanium, and Ti-6Al-4V were probed utilizing real-time velocity interferometry (VISAR) and soft'' shock-recovery techniques. VISAR wave profiles of shock-loaded high-purity titanium revealed the omega-phase pressure-induced transition to occur at approximately 10.4 GPa. Wave profile measurements on A-70 Ti shocked to pressures up to 35 GPa and Ti-6Al-4V shocked to pressures up to 25 GPa exhibited no evidence of a three-wave structure indicative of a pressure-induced phase transition. Neutron and X-ray diffractometry and TEM analysis confirmed the presence of retained {omega}-phase in the electrolytic-Ti and the absence of {omega}-phase in the shock-recovered A-70 Ti and Ti-6Al-4V. Suppression of the {alpha}-{omega} phase transition in A-70 Ti, containing a high interstitial oxygen content, is seen to simultaneously correlate with suppression of deformation twinning. Neutron diffraction was used to measure the in-situ bulk lattice constants and volume fraction of the {alpha} and {omega} phases in the recovered high-purity titanium samples that were shock loaded. The influence of alloy content on the kinetics of formation/retention of {omega}-phase and substructure evolution is discussed and contrasted in light of previous literature studies.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5406462
• Report Number(s): LA-UR-92-887; CONF-920604-2; ON: DE92011138
• Resource Relation: Conference: 7. world conference and exhibition on titanium, San Diego, CA (United States), 28 Jun - 2 Jul 1992
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
TITANIUM
PHASE STABILITY
PHASE TRANSFORMATIONS
TITANIUM BASE ALLOYS
DEFORMATION
SHOCK WAVES
TRANSMISSION ELECTRON MICROSCOPY
ALLOYS
ELECTRON MICROSCOPY
ELEMENTS
METALS
MICROSCOPY
STABILITY
TITANIUM ALLOYS
TRANSITION ELEMENTS
360102* - Metals & Alloys- Structure & Phase Studies