The influence of face coat material on reactivity and fluidity of the Ti6Al4V and TiAl alloys during investment casting

• Tipo: Artigo em Revista Científica Internacional
• Data: 2017

Autores

Neto, RL (Autor) Outra; Teresa P. Duarte (Autor) FEUP; Jorge Lino (Autor) FEUP; Barrigana, TG (Autor) Outra

Revista

Título: Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications

Vol. 231 Nº 1-2

Páginas: 38-48

ISSN: 1464-4207

Editora: SAGE

Indexação

ISI Web of Knowledge - 3 Citações

Scopus - 4 Citações

Outras Informações

ID Authenticus: P-00M-MRZ

DOI: 10.1177/1464420716681824

Abstract (EN): Ti6Al4V alloy belongs to the most significant alloys within the conventional titanium alloys, namely for producing turbochargers impellers and human prostheses. TiAl alloys, because of its attractive properties, such as half density of any nickel-based alloys and excellent high temperature properties, exhibit excellent potential for aerospace turbines and turbocharger turbines application. Investment casting is a near net shape process with great interest for these kind of complex parts, but the processing of these alloys using this technique is still a challenge. In spite of these advantages, these alloys are highly reactive in their molten state, reacting with the ceramic shells used in investment casting, forming a hardened and brittle layer called alpha case on the cast alloy surface, rich in interstitial elements such as oxygen. It is commonly accepted that yttria-based face coats are the best solution for minimizing metal mold reaction, but this ceramic oxide is very expensive. So, the aim of this work is to test alternative materials to produce ceramic shells face coats. A test sample simulating both compressor wheels and turbines was developed and assembled in a wax tree for alpha case and fluidity evaluation. Reactivity studies were conducted based on microhardness measurements and microstructural analysis of gamma-TiAl and Ti6Al4V standard test samples, casted in shells with different face coat materials: fused Y2O3, ZrSiO4, Al2O3, yttria (6%) stabilized ZrO2 and yttria stabilized ZrO2 with 10% fine Y2O3 (3-7 mu m). The results obtained showed that fused Y2O3 face coat eliminates the alpha case, although affecting the fluidity, and gamma-TiAl castings have more misruns blades than Ti6Al4V castings.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 11