EFFECT OF GROWTH RATE ON COARSENING OF SECONDARY DENDRITE ARM SPACINGS IN DIRECTIONALLY SOLIDIFIED OF Al-8.8La-1.2Ni TERNARY ALLOY
Küçük Resim Yok
Tarih
2022
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Polska Akad Nauk, Polish Acad Sciences, Inst Metall & Mater Sci Pas
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
One of the most important factors directly affecting microstructure and mechanical properties in directional solidification process is secondary dendrite arm spacing (SDAS). It is very important to measure the SDAS and examine the factors that may affect them. To investigate the effort of growth rate on the SDAS, the alloy specimens were directional solidified upward with different growth rates ( V= 8.3-83.0 mu m/s) at a constant temperature gradient (G = 4 K/mm) in a Bridgman-type growth apparatus. After the specimens are directionally solidified, they were exposed to metallographic processes in order to observe the dendritic solidification structure on the longitudinal section of the specimens. Coarsen secondary dendrite ann spacings (lambda(2C)) were measured excluding the first arms near the tip of the dendrite. Local solidification times (t(f)) were calculated by ratio of spacings to growth rates. It was detennined that the t(f) values decreased with increasing V values. The relationships between t(f) and lambda(2C) were defined by means of the binary regression analysis. Exponent values of t(f) were obtained as 0.37, 0.43, 0.46 and 0.47 according to increasing V values, respectively. These exponent values are close to the exponent value (0.33) predicted by the Rappaz-Boettinger theoretical model and good agreement with the exponent values (0.33-0.50) obtained by other experimental studies.
Açıklama
Anahtar Kelimeler
Directional solidification, Al-La-Ni ternary alloys, coarsening, secondary dendrite ann spacing
Kaynak
Archives of Metallurgy and Materials
WoS Q Değeri
Q4
Scopus Q Değeri
Q4
Cilt
67
Sayı
3
