A team at the City University of Hong Kong (CityU) has made significant progress in the use of additive manufacturing of titanium alloys with uneven design compositions and creatively proposed a new 3D printing strategy.

The findings were published in Science, a top international journal, with the title In situ design of advanced titanium alloy with concentration modulations by additive manufacturing.

The first author is Zhang Tianlong, a PhD graduate of a joint training program set up by Xi'an Jiaotong University (XJTU) and the City University of Hong Kong.

He is a member of a CityU team led by Liu Chain-Tsuan, an international member of the Chinese Academy of Engineering.

The team controlled the mixing degree of different powders in the molten pool to obtain an unprecedented structure with a micron-level composition gradient, showing a lava-like structure, and producing different scales of β+α' duplex phase microstructure through phase stability modulation. 

The introduction of a plastic effect induced by continuous phase transformation resulted in excellent mechanical properties (1.3GPa tensile strength, 9 percent uniform elongation), providing inspiration for the design of new alloys with uneven compositions.

Lava-like microstructure brought about by micron-scale composition gradient

Researchers creatively combined the concept of composition modulation with 3D printing, and came up with an alloy design strategy with a micron-level composition gradient structure in a different way.

This research has upgraded the inhomogeneity of composition in in-situ alloying in additive manufacturing, and used it to design high-performance alloy material with non-uniform composition. It also greatly expanded the possibilities for additive manufacturing technology, making it a forming technology for complex components and a new alloy design and manufacturing method, thereby effectively promoting additive manufacturing technology to realize integrated intelligent design of "material-structure-performance". 

Zhang has been engaged in the composition and structure design of advanced titanium-based alloys, and has extensive research interests in materials calculation simulation-experimental characterization and other interdisciplinary fields.

He has published more than 10 papers in international academic journals such as Nature and Materials Letters, and has applied for two related patents and software copyrights. He has also served as a reviewer for international journals and magazines.

Link to the paper: https://www.science.org/doi/10.1126/science.abj3770