According to foreign media reports, researchers from the Pacific Northwest National Laboratory (PNNL) of the United States have demonstrated advanced manufacturing technology and directly made nanostructured aluminum rods and tubes using high-performance aluminum alloy powder. The research team adopted a new solid-state processing method, which eliminated several steps of traditional aluminum alloy powder extrusion processing, and significantly improved the ductility of the product, that is, the tensile distance before fracture. That's good news for industries like automobiles. For a long time, the aerospace industry has been using high-performance aluminum alloy made of powder to manufacture lightweight components. However, for the automotive industry, the cost of using these alloys is too high.

The traditional aluminum alloy powder extrusion process has high energy consumption and complex process, which requires multiple steps to mass produce materials. First of all, the loose powder must be put into the tank and then vacuumed. This is called degassing. Then seal the tank, hot press, preheat and put it into the extruder. After extrusion, the tank body is removed or "emptied" to expose the extruded part composed of consolidated powder. In this study, the team removed many steps and used shear assisted machining and extrusion technology (shape) to extrude nanostructured aluminum rods directly from the powder in one step. The powder is poured into an open container, and then the rotating extrusion die is pressed into the powder to generate heat at the interface between the powder and the mold. After softening, the material is easy to extrude without canning, degassing, hot pressing, preheating and decanting. The al-12.4tm aluminum alloy powder in this case was provided by SCM metalworks, a subsidiary of kemela international materials.

Scott Whalen, a PNNL materials scientist, led the study. "This is the first published example of this type, where aluminum alloy powders are solidified into nanostructured extrusions using a single-step process such as shape," he said. Reducing processing steps and heating processes will greatly reduce production time, reduce costs and the energy absorbed inside products, which can help automobile manufacturers to produce cheaper, lighter and more fuel-efficient passenger cars. "

In addition to providing al-12.4tm powder, SCM metalworks also conducted mechanical tests to verify the properties of the extruded material. Currently, PNNL and SCM metalworking companies are working with the technology transformation Office of the U.S. Department of energy to develop projects to expand the processing scale and achieve larger diameter extrusion.

Traditional high performance aluminum alloys usually have high strength but poor ductility. However, the team found that the ductility of the aluminum alloy extruded by the shape technology was significantly improved, which was two to three times that of the conventional extrusion product, and the strength was equivalent. To understand the reason, the microstructure of the powder and extruded material was observed by transmission electron microscopy. The results show that the shape technology can refine the micro strengthening particles of non aluminum materials, reduce their size to nano scale, and evenly distribute on the aluminum matrix, so as to improve the ductility.

Source: International Metal Online