標題: The effects of Mg microaddition on the mechanical behavior and fracture mechanism of MAR-M247 superalloy at elevated temperatures
作者: Bor, HY
Chao, CG
Ma, CY
材料科學與工程學系
Department of Materials Science and Engineering
公開日期: 1-Mar-1999
摘要: The effects of microadditions of Mg on the mechanical behavior and fracture mechanism of MAR-M247 superalloy were investigated in this study. The microstructural observations and image analysis showed that a Mg microaddition ranging from 30 to 80 ppm significantly changed the primary MC carbide characteristics and inhibited the scriptlike carbide formation. After a 80 ppm Mg addition, the elongation measured at 1172 K increased over 3 times found that for the Mg-free MAR-M247 superalloy. The creep life and rupture elongation of the MAR-M247 superalloy with 80 ppm Mg was also improved up to 3 to 5 times that of the alloy without Mg during a 1033 K/724 MPa creep test. The fracture analyses demonstrated that cracks were mainly initiated and propagated at the interface of scriptlike MC carbides in the Mg-free MAR-M247 superalloy at elevated temperatures. The Mg microaddition effectively refined and spheroidized these coarse carbides so that a change in the crack initiation occurred from the carbide/matrix interface to that along the gamma-gamma' eutectic. Interfacial analysis using Auger electron spectroscopy illustrated that Mg segregated to the interface of the MC carbide/matrix, causing a change in the morphology and interfacial behavior of the carbides. This improvement contributed to a prolonged rupture life and upgraded the moderate temperature ductility of the MAR-M247 superalloy.
URI: http://dx.doi.org/10.1007/s11661-999-0047-3
http://hdl.handle.net/11536/31479
ISSN: 1073-5623
DOI: 10.1007/s11661-999-0047-3
期刊: METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
Volume: 30
Issue: 3
起始頁: 551
結束頁: 561
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