TY - JOUR
T1 - Microstructural Characteristics of Unidirectionally Solidified Cast Al–Si–Cu Alloy
AU - Wu, Shaohua
AU - Okayasu, Mitsuhiro
AU - Kuwada, Tatsuya
N1 - Funding Information:
This research was carried out as part of a project of the 2019 Matching Planner Program administered by the Japan Science and Technology Agency (JST). The authors would like to acknowledge the technical support of Mr. Naoki Sahara at Okayama University.
Funding Information:
This research was carried out as part of a project of the 2019 Matching Planner Program administered by the Japan Science and Technology Agency (JST). The authors would like to acknowledge the technical support of Mr. Naoki Sahara at Okayama University.
Publisher Copyright:
© 2020, American Foundry Society.
PY - 2020
Y1 - 2020
N2 - The properties of a conventional Al–Si–Cu alloy (ADC12) material, fabricated using a unidirectional casting process and slowly solidified in the range 0.02–0.14 °C s−1, were determined. The microstructural characteristics of the cast sample were dependent on sample area and resulted from changes in the amount of Si present during solidification. In the lower and middle regions, where the α-Al phase formed relatively organized crystal structures of different patterns, e.g., 〈101〉, columnar grain growth of α-Al dendrites with a low eutectic Si content was observed. Although columnar grain growth was also found in the upper region, it was randomly formed and the area was narrower. Random crystal orientation (i.e., weak control of unidirectional solidification) was created by interrupting columnar α-Al dendrite growth, which resulted from changes in the dynamics of the alloyed Si atoms. Eutectic Si is considered the only Si precipitate in ADC12; however, primary Si was also formed in the middle and upper regions, which was attributed to high Si concentrations resulting from Si migration to the upper region. Fine and coarse microstructures were observed in the lower and upper regions, respectively, with the middle region acting as a transition zone in which the amount of Si rapidly increased following transport between the lower and upper regions. A high amount of hard Si precipitate in the upper region of the sample resulted in high hardness values. In contrast, due to its fine microstructure with unidirectional crystal formation, the lower region exhibited high tensile strength and high ductility.
AB - The properties of a conventional Al–Si–Cu alloy (ADC12) material, fabricated using a unidirectional casting process and slowly solidified in the range 0.02–0.14 °C s−1, were determined. The microstructural characteristics of the cast sample were dependent on sample area and resulted from changes in the amount of Si present during solidification. In the lower and middle regions, where the α-Al phase formed relatively organized crystal structures of different patterns, e.g., 〈101〉, columnar grain growth of α-Al dendrites with a low eutectic Si content was observed. Although columnar grain growth was also found in the upper region, it was randomly formed and the area was narrower. Random crystal orientation (i.e., weak control of unidirectional solidification) was created by interrupting columnar α-Al dendrite growth, which resulted from changes in the dynamics of the alloyed Si atoms. Eutectic Si is considered the only Si precipitate in ADC12; however, primary Si was also formed in the middle and upper regions, which was attributed to high Si concentrations resulting from Si migration to the upper region. Fine and coarse microstructures were observed in the lower and upper regions, respectively, with the middle region acting as a transition zone in which the amount of Si rapidly increased following transport between the lower and upper regions. A high amount of hard Si precipitate in the upper region of the sample resulted in high hardness values. In contrast, due to its fine microstructure with unidirectional crystal formation, the lower region exhibited high tensile strength and high ductility.
KW - EBSD analysis
KW - aluminum alloy
KW - mechanical properties
KW - microstructure
KW - unidirectional solidification
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U2 - 10.1007/s40962-020-00542-y
DO - 10.1007/s40962-020-00542-y
M3 - Article
AN - SCOPUS:85096172540
JO - International Journal of Metalcasting
JF - International Journal of Metalcasting
SN - 1939-5981
ER -