Numerical and experimental investigation of microporosity formation in a ternary Al–Cu–Si alloy

• Published in: Journal of alloys and compounds Vol. 503; no. 1; pp. 31 - 39
• Main Authors: Ferreira, Ivaldo L., Lins, Jefferson F.C., Moutinho, Daniel J., Gomes, Laércio G., Garcia, Amauri
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 30.07.2010; Elsevier
• Subjects: Alloying additive; Aluminum; Aluminum base alloys; Chill casting; Composition fluctuations; Computer simulations; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Growth from melts; zone melting and refining; Materials science; Mathematical models; Metals and alloys; Methods of crystal growth; physics of crystal growth; Microporosity; Permanent molds; Physics; Porosity; Thermal analysis; Metals and alloys; Thermal analysis; Computer simulations; Composition fluctuations; Fluctuations; Directional solidification; X ray fluorescence; Digital simulation; Carbon steels; Iron; Computerized simulation; X-ray spectroscopy; Cast alloy; Transients; Casting; Microporosity; Silicon alloys; Aluminium alloys; Copper alloys; Porosity; Macrosegregation; Crystal growth from melts
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2010.04.244

Macrosegregation and porosity formation are investigated by both a numerical model and transient directional solidification experiments. The macrosegregation pattern, and the theoretical and apparent densities are presented as a function of the casting length. X-ray fluorescence spectrometry was used to determine the experimental macrosegregation profiles. The measurement of microporosity was performed by a pyknometry procedure. The local composition along an Al–6 wt%Cu–1 wt%Si casting length is used as an input parameter for simulations of microporosity evolution. The results show that the addition of 1 wt% silicon to the Al–Cu alloy composition increases significantly the volumetric fraction of pores as compared with the corresponding porosity exhibited by an Al–6 wt%Cu alloy casting. It is also shown that the use of a carbon steel chill mold induced an abnormal increase in the fraction of pores close to the casting cooled surface which was caused by a higher Fe concentration provoked by the diffusive flux of iron from the chill.