Effects of HIP on microstructural heterogeneity, defect distribution and mechanical properties of additively manufactured EBM Ti-48Al-2Cr-2Nb

• Published in: Journal of alloys and compounds Vol. 729; pp. 1118 - 1135
• Main Authors: Seifi, Mohsen, Salem, Ayman A., Satko, Daniel P., Ackelid, Ulf, Semiatin, S. Lee, Lewandowski, John J.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 30.12.2017; Elsevier BV
• Subjects: Additive manufacturing; Analytics; Cloud computing; Compressive strength; Crack propagation; Data management; Defect; Defects; Electron beam melting; Electron beams; Fatigue; Fatigue failure; Fracture mechanics; Fracture toughness; Gamma titanium aluminide; Intermetallic compounds; Mechanical properties; Microstructure; Microstructure evolution; Spatial distribution; Studies; Ti-48Al-2Cr-2Nb; Titanium aluminides; Titanium base alloys; Titanium compounds; Tomography; Gamma titanium aluminide; Ti-48Al-2Cr-2Nb; Tomography; Defect; Fatigue; Additive manufacturing; Electron beam melting; Microstructure evolution; Fracture toughness
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2017.09.163

The present work was conducted to establish an initial understanding of the processing-microstructure-property relations for γ-TiAl manufactured by electron beam powder bed fusion. The investigation included microstructure characterization at different length scales of near-γ titanium aluminide Ti-48Al-2Cr-2Nb (in atom pct) in addition to evaluating the compressive strength, microstructures, fracture toughness, and fatigue crack growth behavior. Micro-CT revealed significant variations in the spatial distribution of internal defects along the build of the as-deposited sample, while HIP reduced these defects. However, inhomogeneous microstructures were exhibited in both the as-deposited and HIP materials while HIP processing reduced both the yield strength and amount of scatter in mechanical properties. Despite these observations, fracture toughness and fatigue crack growth results were in the range of those reported for conventionally cast material. The use of cloud computing provided an efficient means for data management, microstructure analytics, and collaboration among various contributors to the work. •Bulk TiAl produced via EBM.•Microstructure evaluation using large area EBSD to characterize microstructure heterogeneity.•X-ray computerized tomography characterization of as deposited defects and effects of HIP.•Location specific fracture and fatigue behavior.•Effect of HIP treatments on microstructure, defects, and resulting fracture/fatigue behavior.