Cyclic tensile response of Mo-27 at% Re and Mo-0.3 at% Si solid solution alloys

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:676

Article

Yu, X. J.¹  Kumar, K. S.¹ 

[1] Brown Univ, Sch Engn, Providence, RI 02912 USA

关键词: Molybdenum solid solution alloys;    Stress controlled cyclic deformation;    Ratcheting strain;    Dynamic strain aging;   

DOI  :  10.1016/j.msea.2016.08.114

来源: Elsevier

【 摘 要 】

Stress-controlled uniaxial cyclic tensile tests were conducted on binary Mo-27 at% Re and Mo-03 at% Si solid solutions as a function of temperature and compared against the previously reported cyclic response of pure Mo. The Mo-27 at% Re alloy with a recrystallized grain size of 30 gm was evaluated in the temperature range 25 degrees C-800 degrees C at R=0.1 and stress range that was 80% of the ultimate tensile strength (UTS); a peak in fatigue life was observed between 300 degrees C and 500 degrees C. The decrease in fatigue life at the higher temperatures of 700 degrees C and 800 degrees C is attributed to dynamic strain aging. Transmission electron microscopy of the cyclically-deformed alloy revealed parallel bands of dislocation at room temperature that transitioned to a uniform cell structure at 500 C and back to orthogonal planar arrays at 800 degrees C. The as-extruded Mo-0.3 at% Si alloy was evaluated from 25 degrees C to 1200 degrees C and showed superior fatigue life and ratcheting strain resistance as compared to pure Mo and the Mo-27 at% Re alloy (within the temperature range where data were available for comparison). The superior resistance is attributed to the high density of dislocations within the material in this mostly unrecrystallized state rather than Si in solid solution. Above 800 degrees C, the ratcheting strain increases and fatigue life decreases rapidly with increasing temperature and is associated with dynamic recovery. (C) 2016 Elsevier B.V. All rights reserved.

【 授权许可】

Free