Tailoring Microstructures of Metals

In the light of the property requirements to design microstructures will become an important develop direction of metal materials. Here, a new concept of microstructure tailoring is proposed. The main features of microstructure tailoring include designing mesoscale microstructure, establishing quantitative relation between microstructures and properties, accurately inverse-designing and fabricating microstructures to satisfy the property requirements. It means screening, multi-scale calculation, and quantification of the essential microstructural factors should be performed first. Second, the microstructures are purposefully fabricated after adjusting the thermodynamics and kinetics of phase transformation. Third, the microstructures are assessed and tailored through iterative optimization. Microstructure tailoring must be preceded by purification and homogenization of metals. Only when the purity problem of materials is solved first, the influence of inclusions and impurity elements can be eliminated. Only by eliminating the macro-segregation can the material achieve homogeneity. And then the intrinsic properties of the material be fully reflected. As an example of microstructure tailoring, this study investigates the expected fatiguelife requirements of M50 (G80Cr4Mo4V) steels used for bearings in aircraft engines. By controlling the macro-segregation and purification, it is found that the fatigue-life of M50 steel mainly depends on primary carbides. And then the size, type, and morphology of the primary carbides are quantitatively tailored to fulfill the fatigue-life requirement. With technological developments in the metallurgy industry, microstructure tailoring will become a mainstay of the development of metals. And, applying data science and modeling along with microstructure tailoring technology, the alloy design will be gradually optimized in the future. The expensive metal addition will be reduced gradually, so as to save resources and develop green materials.

Automated summary

In the development of metal materials, designing microstructures to meet specific property requirements is crucial. Microstructure tailoring involves designing mesoscale microstructure, establishing quantitative relation between microstructures and properties, and iteratively optimizing and fabricating microstructures to fulfill the desired properties. Purification and homogenization of metals are prerequisites for microstructure tailoring. A case study on M50 (G80Cr4Mo4V) steels used for aircraft engine bearings demonstrated the importance of controlling macro-segregation and purifying metals in tailoring the microstructure for desired fatigue-life requirements. With advancements in technology, microstructure tailoring along with data science and modeling will contribute to optimized alloy design and the development of green materials.