Laser powder bed fusion of Fe-based glassy metal matrix composites

• Grant number: 22/12136-3
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: November 01, 2023
• End date: October 31, 2024
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Claudio Shyinti Kiminami
• Grantee: Aylanna Priscila Marques de Araújo
• Supervisor: Jurgen Hartmut Eckert
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Institution abroad: Montanuniversität Leoben, Austria
• Associated to the scholarship: 20/07692-9 - Fabrication and characterization of Fe-based bulk metallic glass composites produced by additive manufacturing, BP.DR

Abstract

Bulk Metallic Glasses (BMGs) exhibit an aperiodic atomic structure without long-range order, which results in exceptional strength, large elastic limit, excellent magnetic properties, and good corrosion resistance. They are used as micromotors and precision gears for Micro Electro Mechanical Systems (MEMS), automobile valve springs, diaphragms for pressure sensors, power inductors, sporting goods, and fuel cell applications. However, their main issue is the low ductility at room temperature, which results from the nonhomogeneous deformation concentrated in shear bands. Incorporating a ductile second phase in a glassy matrix, forming the named Bulk Metallic Glass Composites (BMGCs), is an alternative to improve their ductility without significantly sacrificing strength. Fe-based BMGs stand out because of their desirable combination of magnetic, corrosion, mechanical properties, and low material cost. Their poor glass forming-ability (GFA) and low ductility are currently the main bottlenecks for producing and applying such materials. The high cooling rates required to produce Fe-based BMGs limit the size and geometry of parts made by casting. This limitation may be overcome by using the additive manufacturing (AM) method of Laser Powder Bed Fusion (LPBF), which is based on locally melting powders deposited on a substrate layer by layer. Because the interaction time between laser beam and powder is very short, high cooling rates (103-106 K/s) can be achieved, and the glassy phase can be formed. Some literature works have shown that the high cooling rates of the LPBF process allow producing Fe-based BMG and BMGCs parts with volume and geometries never obtained before. However, high laser scan speeds are necessary to achieve high cooling rates, which are crucial to glass formation. Additionally, BMGs and BMGCs are sensitive to thermal stress, requiring an LPBF machine with a heated substrate. In this context, the present project aims to investigate the possibility of using the AM process of LPBF for manufacturing Fe-Mo-P-C-B BMGCs and studying their integrity, microstructure and mechanical properties. Nevertheless, the available LPBF machine at DEMa/UFSCar does not achieve the needed laser scan speeds, and neither has a heated substrate, which is essential for glass formation. The present BEPE FAPESP project will allow the student to access LPBF machines with different capacities of laser power, scan speed, and substrate heating, which are available at the facilities of University of Leoben-Austria. Through this internship, access to magnetic test devices and a dual beam microscope able to prepare TEM samples by Focused Ion Beam (FIB) will also occur. The department of materials science of Leoben is a new partner of the DEMa/UFSCar research group and is a well-known research group in the study of structural materials (e.g., steel, alloys, composites, biological materials) aiming for research excellence. The student will stay a year in Leoben/Austria to manufacture Fe-Mo-P-C-B BMGCs by LPBF, which will be partially characterized at the University of Leoben and partially characterized in her return to DEMa/UFSCar. She will be supervised by Prof. Jürgen Eckert, a worldwide authority in the research of bulk metallic glass composites. (AU)