LPBF Processability of NiTiHf Alloys: Systematic Modeling and Single-Track Studies

• Published in: Materials Vol. 17; no. 16; p. 4150
• Main Authors: Dabbaghi, Hediyeh, Pourshams, Mohammad, Nematollahi, Mohammadreza, Poorganji, Behrang, Kirka, Michael M, Smith, Scott, Chinnasamy, Chins, Elahinia, Mohammad
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 22.08.2024; MDPI
• Subjects: Additive manufacturing; Alloy powders; Alloying effects; Alloys; Aluminum; Beds (process engineering); Composition effects; computational modeling; Computer simulation; Computer-generated environments; Cracks; Experiments; Extreme environments; Heat resistant alloys; High temperature; high-temperature shape memory alloys (HTSMAs); Laser beam melting; laser powder bed fusion (LPBF); laser remelting experiments; Lasers; MATERIALS SCIENCE; Mechanical properties; Melting; Powder beds; Powders; processability assessment; Shape memory alloys; Simulation; Solidification; solidification cracking; Solids; Temperature; Germany; laser powder bed fusion (LPBF); solidification cracking; computational modeling; processability assessment; laser remelting experiments; high-temperature shape memory alloys (HTSMAs)
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma17164150

Research into the processability of NiTiHf high-temperature shape memory alloys (HTSMAs) via laser powder bed fusion (LPBF) is limited; nevertheless, these alloys show promise for applications in extreme environments. This study aims to address this limitation by investigating the printability of four NiTiHf alloys with varying Hf content (1, 2, 15, and 20 at. %) to assess their suitability for LPBF applications. Solidification cracking is one of the main limiting factors in LPBF processes, which occurs during the final stage of solidification. To investigate the effect of alloy composition on printability, this study focuses on this defect via a combination of computational modeling and experimental validation. To this end, solidification cracking susceptibility is calculated as Kou's index and Scheil-Gulliver model, implemented in Thermo-Calc/2022a software. An innovative powder-free experimental method through laser remelting was conducted on bare NiTiHf ingots to validate the parameter impacts of the LPBF process. The result is the processability window with no cracking likelihood under diverse LPBF conditions, including laser power and scan speed. This comprehensive investigation enhances our understanding of the processability challenges and opportunities for NiTiHf HTSMAs in advanced engineering applications.