Dresden 2009 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 25: Topical Session High Temperature Materials I

MM 25.2: Topical Talk

Mittwoch, 25. März 2009, 10:45–11:15, IFW A

Deformation Behavior of Mo-Si-B Alloys — •Sharvan Kumar — Division of Engineering, Brown University, Providence, RI 02912, USA

Mo-rich Mo-Si-B alloys are being considered as possible candidates for ultra-high-temperature applications and therefore properties of interest include strength and ductility, toughness and fatigue response of both, the multiphase alloys as well as the Mo solid solution phase. In this presentation, the tensile and compressive creep response of two- and three-phase alloys, crack growth behavior during monotonic and cyclic loading, as well as the contribution of creep in adversely affecting fatigue response will be discussed. These studies helped identify regimes where the microstructure ahead of the crack tip revealed several instabilities including recrystallization, grain growth and creep cavitation. Further, it became apparent from these studies that the Mo(Si,B) solid solution plays a dominant role in influencing toughness and creep resistance, and therefore mandated detailed examination in isolation. Tensile studies on the single phase Mo-Si-B solid solution phase has confirmed dynamic strain aging (DSA), and comparative studies on pure Mo (containing comparable levels of O and C) point to the important role of B and Si in solution on DSA in the solid solution alloy. The presentation will close with a brief discussion on the more recent advances in this alloy system and the challenges, barriers and potential for further development.