Al-based functionally graded super-intermetallic compounds for the turbine blade of a high-performance jet engine

Abstract

An Al-based functionally graded structure is fabricated, featuring a discrete compositional gradient of 48.1Al47.9Ti4.0V/73.7Al24.2Ti2.1V/89.5Al10.0Ti0.5V in atomic percentage. This structure is produced via dual-hybrid laser powder bed fusion and directed energy deposition combined with computer numerical control milling. Particularly remarkable is the high tensile strength, ranging from 0.5 to 1.7 GPa. This strength is attributable to three key factors: (1) rapid solidification during inert gas flow following high-energy laser irradiation, (2) the formation of γ-like intermetallic matrix phases along with γ′-like (α2-based in the composition of 48.1Al47.9Ti4.0V) intermetallic precipitate phases, and (3) the presence of segregates and precipitates with more V-based compounds at the grain boundaries, distinguishable by their sizes, shapes, and distributions across the microstructures. In addition, (4) large anisotropically lamellar precipitate phases, several hundreds of nanometers in diameter, are predominantly observed in the dendritic regions. Owing to these Al-based intermetallic compounds, each exhibiting low densities (2.9−3.7 g cm−3) and high thermal resistances (450−900 °C), the functionally graded structure is then employed in the topological optimization of a turbine blade system for a high-performance jet engine. This process involves identifying the stress-bearing regions, removing any stress-free areas, and applying a structural-stiffness-increasing mechanism through shape and geometric transformation.