Professor Liu’s team recently unveiled the promising possibility of utilizing additive manufacturing to design unique heterogeneous alloys with novel microstructure and supreme properties, which opens a new area in manufacturing for the design of titanium (Ti) alloys that are unachievable by conventional manufacturing methods and that hold great promise for a wide variety of structural applications. His paper was published recently in the prestigious scientific journal Science, titled “In situ design of advanced titanium alloy with concentration modulations by additive manufacturing” [3].
Most people consider 3D printing as a revolutionary technology that can produce machine parts with complex shapes within just one step; however, the research team unveiled that it has important potential in designing materials rather than simply designing geometries.
Metallurgists think that a lack of uniformity in alloy components is undesirable because it leads to harmful properties, such as brittleness. One of the critical issues in the additive manufacturing process is how to eliminate this inhomogeneity during fast cooling. His team found that a certain degree of heterogeneity in the components can actually produce unique and heterogeneous microstructures that enhance the alloy’s properties. The proposed method involves the melting and mixing of two different alloys, i.e., titanium alloy powders and stainless steel powders, using a focused laser beam. By controlling parameters like the laser power and its scanning speed during the 3D printing process, the team successfully created the non-uniform composition of the elements in the new alloy in a controllable way.
In addition to the use of additive manufacturing, the composition of the two powder mixture is another key to creating unprecedented lava-like microstructures with a high metastability in the new alloy. These unique microstructures give rise to the supreme mechanical properties, allowing the alloy to be very strong but ductile, and also in light weight.
While stainless steel is generally 7.9 grams per cubic centimeter, the new alloy is only 4.5 grams per cubic centimeter, resulting in around 40% lighter weight. The titanium alloy with lava-like microstructures exhibited a high tensile strength of ~1.3 gigapascals with a uniform elongation of about 9%. It also had an excellent work-hardening capacity of over 300 megapascals, which guarantees a large safety margin prior to fracture and is useful in structural applications. These excellent properties are promising for structural applications in various scenarios, such as the aerospace, automotive, chemical, and medical industries.
The titanium alloy developed by Professor Liu’s team is super-strong, highly ductile and ultra-light [3].
Reference
1. Yang, T, Zhao, YL, Li, WP, Yu, CY, Luan, JH, Lin, DY, Fan, L, Jiao, ZB, Liu, WH, Liu, XJ, Kai, JJ, Huang, JC & Liu, CT 2020, 'Ultrahigh-strength and ductile superlattice alloys with nanoscale disordered interfaces', Science (New York, N.Y.), vol. 369, no. 6502, pp. 427-432.
2. Yang, T, Zhao, YL, Tong, Y, Jiao, ZB, Wei, J, Cai, JX, Han, XD, Chen, D, Hu, A, Kai, JJ, Lu, K, Liu, Y & Liu, CT 2018, 'Multicomponent intermetallic nanoparticles and superb mechanical behaviors of complex alloys', Science (New York, N.Y.), vol. 362, no. 6417, pp. 933-937.
3. Zhang, T, Huang, Z, Yang, T, Kong, H, Luan, J, Wang, A, Wang, D, Kuo, W, Wang, Y & Liu, C-T 2021, 'In situ design of advanced titanium alloy with concentration modulations by additive manufacturing', Science, vol. 374, no. 6566, pp. 478-482.