Hong Kong Scientists Develop Miniature 3D Printing To Create Super Strong Titanium Alloys
A study led by scientists at the City University of Hong Kong used additive manufacturing (commonly referred to as 3D printing) to successfully develop a super-strong, high-ductility, and super-light titanium-based alloy. Their discovery opened up a new way to design alloys with unprecedented structures and properties for various structural applications.
3D printing: more than just a molding technology
Most people think that 3D printing is a revolutionary technology that can produce complex-shaped machine parts in one step. "However, we have revealed its important potential in designing materials, rather than simply designing geometric figures. Metallurgists tend to believe that the lack of uniformity in alloy composition is undesirable because it can lead to undesirable properties such as brittleness. In the additive manufacturing process, how to eliminate the unevenness in the rapid cooling process is one of the key issues.
Design a unique microstructure
"The unique characteristics of additive manufacturing provide us with greater freedom in designing microstructures," explained Dr. Zhang, who is also the first author of this paper. "Specifically, we have developed a partial homogenization method that uses 3D printing technology to produce alloys with micron-level concentration gradients, which cannot be achieved by any traditional material manufacturing method."
The method they proposed includes using a focused laser beam to melt and mix two different alloy powders and stainless steel powders. By controlling parameters such as laser power and scanning speed during the 3D printing process, the team succeeded in creating a non-uniform composition of elements in the new alloy in a controlled manner.
(3D printed grain orientation map of titanium alloy)
Professor Liu said: In addition to the use of additive manufacturing, the composition of the two powder mixtures is another key to creating an unprecedented high metastable lava-like microstructure in the new alloy. These unique microstructures bring the highest mechanical properties, making the alloy very tough and light in weight. The experimental results show that the new titanium alloy has excellent mechanical properties.
New alloy: 40% lighter, super strength
Generally speaking, the mass of stainless steel is 7.9 grams per cubic centimeter, while the mass of the new alloy is only 4.5 grams per cubic centimeter, which is about 40% lighter. In their experiments, the titanium alloy with a lava-like structure exhibited a high tensile strength of ~1.3 gigapascal, with a uniform elongation of about 9%. It also has an excellent work hardening ability of more than 300MPa, which ensures a huge safety margin before fracture, which is very useful in structural applications.
These excellent properties have good structural application prospects in various situations, such as aerospace, automotive, chemical, and medical industries. As the first team to use 3D printing technology to develop a new alloy with a unique microstructure and properties, we will further apply this design concept to different alloy systems and further explore other properties of the new alloy.
