Enhancement in strength and thermal stability of selective laser melted Al–12Si by introducing titanium nanoparticles

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 855; p. 143833
• Main Authors: Qi, J.F., Liu, C.Y., Chen, Z.W., Liu, Z.Y., Tian, J.S., Feng, J., Okulov, I., Eckert, J., Wang, P.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 10.10.2022; Elsevier BV
• Subjects: Additive manufacturing; Al alloys; Alloying; Aluminum base alloys; Annealing; Grain size; Heat treatment; High temperature; Laser beam melting; Mechanical properties; Microstructure; Nanoalloys; Nanoparticles; Performance degradation; Silicon; Structural stability; Thermal stability; Titanium base alloys; Yield strength; Yield stress; Mechanical properties; Heat treatment; Additive manufacturing; Al alloys; Microstructure
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2022.143833

Due to the rapidly degradative mechanical performance of selective laser melted (SLM) Al–12Si at elevated temperatures, an Al–12Si–Ti alloy was synthesized by SLM processing with a powder mixture consisting of Al–12Si and 1 wt% of Ti nanoparticles to improve its thermal stability at mid-temperatures (573 K). The results demonstrate that the addition of Ti nanoparticles (i) enlarges the parameter window of SLM processing (power inputs of 200–350 W and scanning speeds of 600–1600 mm/s), (ii) stimulates a columnar to equiaxed transition and refinement of grains (average grain size decreases from 9.0 μm to 1.5 μm), (iii) forms Al3Ti phase improving the thermal stability of Al–Si eutectic cell structure, and (iv) partially suppresses the precipitation of Si phase and coarsening of cell structure at elevated temperatures. These features lead to an improved yield strength of SLM Al–12Si–Ti compared with SLM Al–12Si. Specifically, SLM Al–12Si–Ti annealed at 573 K possesses a higher yield strength (297 ± 10 MPa) than SLM Al–12Si (207 ± 9 MPa) annealed at the same conditions. This study will pave the way for the design and synthesis of SLM Al alloys with improved structural and mechanical stability by minor alloying via nanoparticle addition. •Al–12Si–Ti alloy with a broad processing window is designed and fabricated by selective laser melting (SLM).•SLM Al–12Si–Ti alloy has high microstructural stability as well as mechanical performance under an annealing temperature of 573K.•Addition of Ti can promote the columnar to equiaxed transition and refinement of grains.•Addition of Ti leads to the formation of Al3Ti precipitates enhancing the thermal stability of eutectic Al–Si cell structure.•Addition of Ti can suppress microstructural change, thereby maintaining a higher strength than Al–12Si under an annealing temperature of 573K.