A radically new approach to laser additively manufacture metals with periodic coarse-fine grain structures for breaking the strength-ductility trade-off

ongoing

Periodic lamellar metals (PLMs) with coarse-to-fine grained microstructures provides a new way to overcome the strength-ductility trade-off through the accumulation of geometrically necessary dislocations and hetero-deformation induced hardening, demonstrating great potential to future engineering applications. As an important component of Industry 4.0, selective laser melting (SLM) has become a powerful industrial tool in EU and worldwide. However, to date, few to no efforts have been devoted into the experimental investigation of PLMs made by SLM. Only one modeling work briefly discussed the strengthening and toughening mechanisms of the PLMs. Thus, the fundamental knowledge associated with the microstructures and properties of SLM PLM parts is still lacking. Such lack of critical knowledge is a hard barrier for the development of high-performance PLM engineering parts. To this end, this project proposes to adopt SLM for the fabrication of novel PLMs through adding alloying elements into starting powders. The key aspects of this proposal are as follows: 1) Design and fabrication of PLMs; 2) Microstructural tailoring and anisotropic tensile evaluation; 3) Characterization of the strengthening and toughening mechanisms; 4) Prediction of anisotropic tensile properties by machine learning. This project aims to evolve the current in-situ alloying strategy employed during SLM, enable the tailoring of heterogeneous microstructures, and provide an excellent strength-ductility balance over the homogeneous-grained counterparts. It is expected that the new knowledge generated from this project will facilitate the 3D printing of high-performance metals. This proposal involves both the transfer of knowledge to the host institution and the training of the candidate in new advanced techniques. The expected results have the potential capacity to increase the competitiveness and provide room for further studies at both the fundamental and applied levels in additive manufacturing.