The team of Professor Chen Xizhang of Wenzhou University broke through the multi-stranded wire additive manufacturing high-entropy alloy manufacturing technology for the first time, providing an efficient and promising manufacturing method for the manufacture of large-size and complex-shaped high-entropy alloy materials and products. The manufactured Al- The Co-Cr-Fe-Ni high-entropy alloy achieves an excellent combination of strength of 2.8 GPa and elongation of 42%.
High-entropy alloys have been proposed for more than ten years. Due to breakthroughs in theory and performance, it has been one of the research focuses of researchers. Among them, additive manufacturing has received attention from researchers and industrial fields due to its unique advantages. The materials used in additive manufacturing are mainly powder and wire. For high-entropy alloys, it is mainly powder at present, which is used for selective laser melting (SLM), laser cladding (LMD), and selective electron beam melting (SEBM) and Plasma Arc Additive Manufacturing (PPAW), etc. Wire is the main raw material for direct deposition additive manufacturing. It is especially suitable for the manufacture of large-scale components. It has the advantages of high efficiency and high product utilization. However, high-entropy alloys cause problems such as fluidity and segregation due to the complex shape of the composition. The manufacturing of size products is precisely its pain point and limits the industrial application of the material. However, due to various technical difficulties, the preparation of high-entropy alloy wires has not been realized so far, which has become a bottleneck technology, which greatly limits the application of this high-end material.
Recently, the "Advanced Connection and Additive Manufacturing" research team of Professor Chen Xizhang of the School of Mechanical and Electrical Engineering of Wenzhou University, calculated various elemental or alloy wires according to the design composition and twisted them into a single stranded wire (the author named CCW) , Using the wire as the filling material and the electric arc as the energy source to realize the additive manufacturing of high-entropy alloy products. Relevant research results were published in "Journal of Materials Science & Technology" with the title "Fabrication of bulk Al-Co-Cr-Fe-Ni high-entropy alloy using combinedcable wire arc additive manufacturing (CCW-AAM): Microstructure and mechanicalproperties". 2021) 136-142
Paper link: https://doi.org/10.1016/j.jmst.2020.10.037
The wire prepared by the team is made by twisting a variety of elemental or alloy wires, successfully avoiding the difficulty of preparing high-entropy alloy wires. The article involves stranded wire made of 7 elemental and alloy wires, which are twisted by a special process, with a diameter of 1.8mm. Al-Co-Cr-Fe is successfully prepared by cold metal transition (CMT) arc additive technology. -Ni non-equal atomic ratio high-entropy alloy.
The high-entropy alloy of the Al-Co-Cr-Fe-Ni system achieves solid solution strengthening through the lattice distortion caused by the difference between the atomic radius of aluminum and the other elements. In this experiment, the arc-passing additive manufacturing is to prepare a non-molar ratio Al-Co-Cr-Fe-Ni high-entropy alloy. The printed sample is composed of FCC and BCC dual phases, where BCC is rich in Al-Ni phase and FCC is rich in Fe-Cr.
The experiment studied the effect of heat on the microstructure and properties of high-entropy alloy samples by changing the deposition rate. It is found through experiments that the faster the torch runs (the less the heat input), the smaller the grain size of the prepared sample, the less the heat input is reflected in the mechanical properties, and the yield strength, fracture strength and toughness have a certain degree Improve (breaking strength: 2835 MPa, elongation: 41.8%).
In order to verify the product performance, the wire was directly used as a raw material for smelting, ensuring the same composition, and comparing it with the additive manufacturing sample. Compared with the smelted samples, it is found that due to the slow heat dissipation of the smelting, the crystal grains are coarse and severely embrittlement, and the fracture strength and toughness are far inferior to the samples manufactured by additive materials. This fully reflects the superiority of additive manufacturing.
It is reported that the team aims to make breakthroughs in the manufacturing and industrial application of large-size bulk materials and complex-shaped high-entropy alloy product components. Since 2016, the team proposed the concept of high-entropy alloy stranded wire additive manufacturing, and has broken through many key technologies. , Successfully mastered the preparation process of a variety of high-entropy alloy stranded wires, and successfully adopted cold metal transition (CMT), plasma arc, laser and other direct wire deposition methods to realize the direct deposition additive manufacturing of high-entropy alloy stranded wires.