ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
It has been elucidated that the small creep strain must be essential to form the rafted γ/γ'structure using a single crystal nickel-based superalloy, CMSX-4. To confirm the amount of thestrain required to make rafting, the single crystals interrupted the creep tests up to a strain of 0.01 at1273K-250MPa was aged at 1273K without stress. To compare the difference in the morphology ofthe γ/γ' structure of the as-heat treated and the creep-interrupted single crystal with the simple aging,the as-heat treated single crystal was also aged. Microstructural observations by SEM wereconducted for the specimens sectioned parallel to (100). The cuboidal γ' precipitates of the as-heattreated single crystal connected each other with three 〈100〉 directions after the simple aging. Byemploying the aging without stress on the specimen interrupted the creep test at a strain of 0.0074,the drastic morphological change in the γ/γ' structure was confirmed, that is, the γ/γ' structurechanged to rafted one perpendicular to the creep-interrupted stress axis. The aspect ratios of thecreep-interrupted specimens increased with increasing simple aging time, and attained to themaximum value at the simple aging time of 3.60x106s. The maximum value of the aspect ratiosincrease with increasing creep-interrupted strain and attained 4 at a strain of 0.0074. The dislocationdensity at the γ/γ' interface increases with increasing creep strain. Consequently, the formation ofthe rafted γ/γ' structure requires the dislocation substructure induced by the creep strain
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/15/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.3024.pdf
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