The onset of grain refinement temperature in undercooled Ge

Journal Article · Mon May 15 04:00:00 EDT 1995 · Scripta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-716X(95)00258-W· OSTI ID:69664

Wong, P C; Leung, K K; Lau, C F; Kui, H W ^[1]

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1. Chinese Univ. of Hong Kong, Shatin (Hong Kong). Dept. of Physics

When an undercooled specimen crystallizes, its microstructure depends on the initial bulk undercooling, {Delta}T = T{sub m} {minus} T where T{sub m} is its thermodynamic melting temperature. At {Delta}T near but smaller than 200 K, a typical undercooled Ge specimen exhibits an ordered and connected structure, in which the various dendrites are arranged side by side in a very orderly way. Indeed, the entire surface of this specimen is covered with this regular dendritic pattern. Another undercooled specimen with {Delta}T = 206 K, on the other hand, illustrates a small region inside which the grains are more or less randomly oriented. It appears that these grains are fragments of dendrites scattered all over the region where contact had been made with the fused silica rod. Furthermore, the size of the grains near this region is smaller than those further away indicating grain refinement has just occurred in this region. Summing up, it can therefore be concluded that the onset of grain refinement in undercooled Ge lies between {Delta}T = 201 and 206 K which is substantially smaller than the previous value, 230 K. For simplicity, the onset of grain refinement temperature is chosen to be 203 K.

• OSTI ID: 69664
• Journal Information: Scripta Metallurgica et Materialia, Journal Name: Scripta Metallurgica et Materialia Journal Issue: 10 Vol. 32; ISSN 0956-716X; ISSN SCRMEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CRYSTALLIZATION
DENDRITES
GERMANIUM
GRAIN REFINEMENT
GRAIN SIZE
LIQUID METALS
MICROSTRUCTURE
NUCLEATION
SAMPLE PREPARATION
TEMPERATURE DEPENDENCE