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Evidence of heterogeneous substructure development during primary creep of Ti-6Al-2Sn-4Zr-2Mo

Journal Article · · Scripta Metallurgica et Materialia
 [1];  [2];  [3]
  1. Metals Technology, Inc., Northridge, CA (United States)
  2. Rockwell International Corp., Thousand Oaks, CA (United States)
  3. California Polytechnic State Univ., San Luis Obispo, CA (United States)
Preliminary creep tests conducted on the titanium alloy Ti-6Al-2Sn-4Zr-2Mo show that both primary creep strain and the minimum strain rate decreases with decreasing volumes of primary alpha phase in the microstructure. This is in agreement with well established trends. The authors have suggested a relationship between the initial dislocation source density and the primary creep behavior and have pointed toward some microstructural variables which may give rise to a high initial dislocation source density. Measurements of anelastic backflow and the characterization of the kinetics of the backflow process indicates that the Ti-6Al-2Sn-4Zr-2Mo exhibits very similar behavior to that of pure FCC aluminum, copper and lead. It is suggested that the anelastic backflow provides direct evidence of a heterogeneous substructure and a nonuniform distribution of stresses within the material which drives the backflow process. The backflow process is discussed along the lines of what has been discussed regarding time dependent anelastic backflow in high purity FCC Metals. Finally, the apparent creep activation energy estimated from creep tests at two temperatures at constant initial applied stress indicates that creep under the present experimental conditions is diffusion controlled. At present no specific mechanism can be defined. More definitive and extensive work is planned in order to better address the issues regarding primary creep in titanium alloys.
OSTI ID:
27985
Journal Information:
Scripta Metallurgica et Materialia, Journal Name: Scripta Metallurgica et Materialia Journal Issue: 6 Vol. 32; ISSN SCRMEX; ISSN 0956-716X
Country of Publication:
United States
Language:
English