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http://dx.doi.org/10.3365/KJMM.2011.49.1.058

Effects of Initial Nucleation Condition at the Start Block on the Grain Size and Growth Direction in Directionally Solidified CM247LC Superalloy  

Yoon, Hye-Young (Dept. of Materials Science and Engineering, Changwon National University)
Lee, Je-Hyun (Dept. of Materials Science and Engineering, Changwon National University)
Jung, Hyeong-Min (Dept. of Materials Science and Engineering, Changwon National University)
Seo, Seong-Moon (High Temperature Materials Lab., Korea Institute of Materials)
Jo, Chang-Young (High Temperature Materials Lab., Korea Institute of Materials)
Gwon, Seok-Hwan (R&D Center, Korea Lost Wax Co.)
Chang, Byeong-Moon (R&D Center, Korea Lost Wax Co.)
Publication Information
Korean Journal of Metals and Materials / v.49, no.1, 2011 , pp. 58-63 More about this Journal
Abstract
The grain size and growth direction of a directionally solidified turbine blade were evaluated by the initial nucleation condition at the start block of directional solidification. The initial nucleation condition was controlled by inserting a Ni foil on the directional solidification plate of the directional solidification furnace. Fine grains with good orientation were obtained in the faster cooling condition at the start block. The nucleus number was compared with the cooling rate of the start block by electron back scattered diffraction (EBSD). DSC (differential scanning calorimeter) analysis was performed to compare the melting point and undercooling for nucleation of the coarse nuclei and fine nuclei of the start block. The faster cooling condition at the start block showed more undercooling for nucleation and smaller size of nuclei which resulted in a fine grain with good orientation in the directional turbine blade.
Keywords
directional solidification; cooling condition; nucleation condition; EBSD; DSC; CM247LC;
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