Metal 3D printing technology (also known as additive manufacturing) can efficiently manufacture complex geometric structures and reduce losses. It is very attractive for high-temperature alloys, especially for porous or hollow aerospace components. On May 11th, the team of academician Roger Reed was invited to publish a review article titled "Metal 3D printing as a disruptive technology for superalloys" in the top journal "Nature Communications" to review the history of superalloys and discuss 3D printing on superalloys. Challenge and look forward to the future development of this direction.
Paper link:
https://www.nature.com/articles/s41467-020-16188-7
High temperature alloy, also known as superalloy, is widely used in the core components of the aerospace and energy fields. Its design is usually made of nickel / cobalt / iron as the matrix, and it is strengthened by adding a variety of elements, so that it has excellent high temperature performance and organizational stability, and can be used for a long time under extreme working conditions. However, the manufacturing process window of high-temperature alloys is very narrow, usually after long and expensive and complicated processes, and then through machining to obtain the final parts.
Metal 3D printing technology can reduce consumables, and save a lot of molds, and realize (near) net shaped parts through digital design. However, there are many challenges here. After the general metal material adopts 3D printing technology, such as laser selective melting (SLM), its mechanical properties will suffer from varying degrees of loss, which is mainly due to the formation of various defects, such as micro-cracks, bubbles, etc. This is extremely important for superalloys, because the failure mode of service parts is usually creep or fatigue fracture, and these properties are very sensitive to defects, so it is necessary to fundamentally suppress the occurrence of these defects.
The main challenges can be divided into scientific and technical issues. Because 3D printing itself is a multi-physics problem and it spans different time and space scales. For example, during the movement of the heat source in the powder bed, the four forms of solid, liquid, gas, and plasma can interact simultaneously. Very few physical models currently cover this complexity. At the same time, there are many challenges in the process that still need to be solved. The following figure summarizes the main points, such as efficient dynamic real-time monitoring, non-destructive testing, and high-throughput testing.
Faced with the extremely high rate of thermal cycling and remelting in additive manufacturing, existing high-temperature alloys are difficult to adapt, after all, this is very different from the traditional alloy design concept. Therefore, in order to effectively use the convenience of metal 3D printing technology, it is indispensable to design new alloy components that can be applied to additive manufacturing. At the same time, the data-driven approach is expected to provide better solutions in physics and process simulation. The formulation and implementation of comprehensive industrial standards can also inject momentum into the industry.