Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals

Michael J. Mills

关键词: AIRCRAFT;    ALLOYS;    CREEP;    DISLOCATIONS;    EFFICIENCY;    ENERGY CONVERSION;    ENGINES;    GAS TURBINES;    HEAT RESISTING ALLOYS;    MICROSTRUCTURE;    MONOCRYSTALS;    ORIENTATION;   

DOI  :  10.2172/948728
RP-ID  :  DOE/FG/ER46137
PID  :  OSTI ID: 948728
Others  :  TRN: US201006%%478

学科分类：材料科学（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

Cast nickel-based superalloys are used for blades in land-based, energy conversion and powerplant applications, as well as in aircraft gas turbines operating at temperatures up to 1100 C, where creep is one of the life-limiting factors. Creep of superalloy single crystals has been extensively studied over the last several decades. Surprisingly, only recently has work focused specifically on the dislocation mechanisms that govern high temperature and low stress creep. Nevertheless, the perpetual goal of better engine efficiency demands that the creep mechanisms operative in this regime be fully understood in order to develop alloys and microstructures with improved high temperature capability. At present, the micro-mechanisms controlling creep before and after rafting (the microstructure evolution typical of high temperature creep) has occurred have yet to be identified and modeled, particularly for [001] oriented single crystals. This crystal orientation is most interesting technologically since it exhibits the highest creep strength. The major goal of the program entitled ''Mechanisms of High Temperature/Low Stress Creep of Ni-Based Superalloy Single Crystals'' (DOE Grant DE-FG02-04ER46137) has been to elucidate these creep mechanisms in cast nickel-based superalloys. We have utilized a combination of detailed microstructure and dislocation substructure analysis combined with the development of a novel phase-field model for microstructure evolution.