As the increasing popularity of 3D printing manufacturing technology, engineers are now trying to 3D print different materials together to manufacture cost-effective and sustainable parts for the aerospace industry. Including Lockheed Martin and Boeing, as well as some subcontractors in the aerospace and defense field, government research institutions and university laboratories are exploring how to print a variety of materials, especially 3D printing different metal materials. This can produce some parts that meet special functional requirements, including one end that is very hard and the other end that has superior thermal conductivity. Although 3D printing with multiple materials is still in its infancy, this field is full of possibilities. Because the application of multiple materials can give engineers more freedom to achieve design requirements, in the Air Force Research Laboratory, researchers are focusing on the research of multi-material 3D printing. This one-time completed part breaks through the traditional processing Due to the constraints of methods, traditional processing methods need to manufacture parts of different materials one by one, and then combine them by welding or assembly. Not only is the Air Force Research Laboratory, Penn State University’s Innovative Materials Processing Center is also fusing different metal materials into a single part through a direct digital deposition process. According to the responsible Rich Martukanitz of the Applied Research Laboratory of Pennsylvania State University, the laboratory is providing research on corrosion-resistant materials for the U.S. Navy. Through 3D printing, nickel-based materials can only be added to areas that require high corrosion or abrasion. Of course, some metals are not easy to be mixed together, including aluminum and titanium. Engineers prefer to use aluminum material because of its low density, but in some places where low weight and high strength are particularly required, titanium materials are still needed. Therefore, if the two materials of titanium and aluminum are made into a part by 3D printing, and the use of titanium is increased in the parts that require high strength, this will bring a disruptive change to the current part manufacturing. CIMP-3D is developing a method to grade each material element to avoid unnecessary waste of time when printing a new part. Understanding 3D printing multi-materials from metallurgy is a research direction. By grading each material, CIMP-3D can systematically conduct 3D printing research on multiple materials. According to Leo Christodoulou of Boeing Defense, although 3D printing technology is constantly changing and developing, yesterday's processing technology is different from today's processing technology. However, in the past few years, these processes still have a certain degree of stability, so material research based on processing technology not only requires an understanding of the metallurgical properties of materials but also an understanding of processing technology and the application of the software.