Tailoring microstructure of lightweight refractory compositionally complex alloy via selective laser melting

Guest Speaker：Research group leader Jin Wang, Forschungszentrum Jülich, Germany

Inviter: Ass.Prof. Chao Yang

Date&Time: Tuesday, 15th July, 10:45-12:00

Venue: Yiucheng Lecture Hall (500), Xu Zuyao Building

Biography:

Jin Wang received her Bachelor degree from Hefei University of Technology (China), and her Master and Ph.D. degrees from Karlsruhe Institute of Technology (Germany) in Material Science and Engineering, and Mechanical Engineering. Her research interests are mechanical size effects, microstructure correlated mechanical behavior, and microstructure design for high-performance metals. In 2021, she defended her dissertation of “Characterization of the size-dependent indentation behavior and dislocation structures of single-crystalline tungsten” at Karlsruhe Institute of Technology with distinction (summa cum laude). From 2020, she joined Forschungszentrum Jülich (Federal Research Centre, Germany) as a research associate. Since 2024, she leads a research group “Microstructure design for high-performance metals” at Institute of Energy Materials and Devices, Structure and Function of Materials (IMD-1), Forschungszentrum Jülich.

 Abstract:

 Al-containing refractory compositionally complex alloys (RCCAs) such as NbMoCrTiAl were designed as materials with low density and superior mechanical performance for lightweight applications at elevated temperatures. While the Al addition reduces the alloy density, the Al-containing RCCAs tend to form brittle intermetallic compounds and secondary phases including the ordered BCC phase (B2 type), Laves, and A15 phases. This is related to the secondary ordering transformation due to the limited cooling rate in conventional processing, e.g., arc-melting and casting.

We applied selective laser melting (SLM) to tailor the microstructure of NbMoCrTiAl without reducing the amount of Al, thereby maintaining the reduced density. 4D-STEM and APT confirmed that the initial microstructure consisting of the B2 matrix with grain boundary precipitates was replaced by a homogeneous BCC phase (A2 type) after SLM treatment. Correlative microstructural and mechanical characterization, i.e., EBSD and high-throughput nanoindentation analyses, were applied to understand the dependence of the microstructures on the process parameters and the resulting properties.