2024 1st 3D printing nature

The first Nature article in the field of 3D printing technology in 2024 was published on February 27th. A team of researchers from the Institute of Metals, Chinese Academy of Sciences (IMS) published an article titled "High fatigue resistance in a titanium alloy via near void-free 3D printing".

The article argues that the underlying 3D printed microstructures have a naturally high fatigue resistance, and that the degradation of this property may be caused by the presence of micropores. Conventional efforts to eliminate micropores often result in tissue coarsening, while the process of tissue re-refinement brings about the recurrence of porosity and even triggers new disadvantages such as the enrichment of α-phase at grain boundaries, making the microstructures dilemma of in-and-out efforts.
During the heat treatment research conducted by the CAS team, a key post-treatment process window was discovered, where the phase transition and grain growth of 3D printed titanium alloys at high temperatures are asynchronous. With sufficient superheat, the α to β phase transition occurs immediately, and although the β phase growth temperature has been reached, the grain boundaries need a gestation period to rearrange themselves. Taking advantage of this valuable heat treatment window, the researchers determined a heat treatment method combining hot isostatic pressing and high-temperature short-time treatment, which both achieved tissue refinement and prevented α-phase enrichment as well as the reappearance of micropores, and ultimately prepared near-printed state 3D printed titanium alloys that are almost free of micropores.

TC4 titanium alloys with this microstructure achieve a high fatigue limit of about 1 GPa, exceeding the fatigue resistance of all current additively manufactured and wrought titanium alloys, as well as other metallic materials.