Impact of microstructural stability on the creep behavior of cast Al-Cu alloys

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

卷:772

Article

Milligan, Brian K.^1,2  Roy, Shibayan^1,3  Hawkins, Charles S.¹  Allard, Lawrence F.¹  Shyam, Amit¹ 

[1] Oak Ridge Natl Lab, Mat Sci & Technol Div, 1 Bethel Valley Rd,Bldg 4500S, Oak Ridge, TN 37830 USA

[2] Colorado Sch Mines, Met & Mat Engn Dept, 920 15th St, Golden, CO 80401 USA

[3] Indian Inst Technol Kharagpur, Mat Sci Ctr, Kharagpur 721302, W Bengal, India

关键词: Aluminum alloys;    Creep;    Aluminum-copper;    Grain boundary;   

DOI  :  10.1016/j.msea.2019.138697

来源: Elsevier

【 摘 要 】

Creep behavior of three cast Al-Cu alloys at 300 degrees C was studied by measuring their steady state creep rates as a function of stress. Microalloying additions in two alloys stabilized the theta' (Al2Cu) precipitates to 300 degrees C, which allowed grain boundary-controlled creep deformation to dominate at low stresses in these alloys. In contrast, the instability of the microstructure at 300 degrees C in a conventional Al-Cu 206 alloy led to the majority of theta' precipitates transform to the theta phase. The 206 alloy displayed diminished resistance to dislocation motion and a dislocation creep mechanism dominated from the lowest stresses. A modified Coble creep model was developed to describe the experimental low-stress creep rates in the alloys with thermally stable precipitate structures. It is concluded that increasing the thermal stability of precipitates in Al-Cu alloys can provide significant improvement in their creep performance.

【 授权许可】

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