Titanium alloys have excellent corrosion resistance, high temperature strength, low density, and biocompatibility. Therefore, they are increasingly used for aerospace, biomedical, and chemical applications. Investment casting is a well-established process for manufacturing near-net-shape intricate parts for such applications. However, mass transfer arising from metal-mold reactions is still a major problem that drastically impairs the surface and properties of the castings. Although there have been astounding developments over the past 20 years, they remain scattered in various research papers and conference proceedings. This review summarizes the current status of the field, gaps in the scientific understanding, and the research needs for the expansion of efficient casting of titanium alloys. The uniqueness of this paper includes a comprehensive analysis of the interfacial reactions and mass transfer problems. Additionally, momentum and heat transfer are presented where applicable, to offer a holistic understanding of the transport phenomena involved in investment casting. Solutions based on modeling and experimental validation are discussed, highlighting ceramic oxide refractories like zirconia, yttria, calcia, alumina, and novel refractories namely, calcium zirconate and barium zirconate. It was found that while mold material selection is vital, alloy composition should also be carefully considered in mitigating metal-mold reactions and mass transfer.
R. S. Uwanyuze et al., "A Review On Alpha Case Formation And Modeling Of Mass Transfer During Investment Casting Of Titanium Alloys," Journal of Alloys and Compounds, vol. 865, article no. 158558, Elsevier, Jun 2021.
The definitive version is available at https://doi.org/10.1016/j.jallcom.2020.158558
Materials Science and Engineering
Keywords and Phrases
alpha-case; Corrosion; Investment casting; Mass transfer; Metal-mold reactions; Refractories; Titanium alloys
International Standard Serial Number (ISSN)
Article - Journal
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05 Jun 2021