Assistant Professors Ashwin Shahani, John Heron and Liang Qi are all 2019 NSF CAREER Award recipients.

Assistant Professors Ashwin Shahani, John Heron, and Liang Qi.

CONGRATULATIONS to Assistant Professors Ashwin Shahani, John Heron and Liang Qi for recently receiving CAREER Awards from NSF-DMR (Division of Materials Research). Shahani received the award for his proposal: “Microstructure Formation in Chemically-Modified Eutectics: Bridging Real-Time Imaging, Machine Learning, and Problem-Based Instruction.” Heron’s award was for his proposal titled, “Understanding disorder, defects, and dielectric properties of entropy-stabilized oxides," and Assistant Professor Liang Qi received the grant for “First-Principles Predictions of Solute Effects on Defect Stability and Mobility in Advanced Alloys.” (See non-technical summaries below.)

"Winning an NSF CAREER Award is a special occurrence," said Amit Misra, chair of MSE, "but to have three winners in one year - that's really rare."

NON-TECHNICAL SUMMARY for Assistant Professor Ashwin Shahani: "Microstructure Formation in Chemically-Modified Eutectics: Bridging Real-Time Imaging, Machine Learning, and Problem-Based Instruction.”

Patterns in nature typically form when a system changes from one phase of matter to another - for example, from a liquid phase to a geometrically patterned solid phase during solidification. The resulting patterns resemble a labyrinth of streets in a metropolitan area, although they are approximately one-hundred million times smaller and in three dimensions, called crystals. The structures of the as solidified crystals arranged in the pattern closely relate to the properties of the material, even after subsequent processing steps. To our advantage, the shapes and sizes of these crystals can be tailored to meet technological demands by manipulating the chemical composition of the parent liquid phase. For instance, trace metal impurities dissolved in the liquid are known to transform solid silicon (Si) from coarse, blocky particles into fine, web-like fibers. This results in a dramatic enhancement of the strength and ductility of the Si-based alloy and expands its potential for new applications, including space-frames and electric vehicles. The objective of this CAREER award is to understand how and why such transformations occur in the presence of trace metal impurities, by harnessing one of the brightest sources of hard X rays in the world at Argonne National Laboratory. The incident X-radiation can penetrate through an otherwise opaque metal, allowing one to capture the details of solidification in real time. Following the experiments, the PI and his team will extract information from the time lapse videos of solidification using state-of-the-art machine learning algorithms. It is anticipated that their new vision will advance the field of alloy solidification from metallurgical alchemy to predictive science. Ultimately, understanding the evolution of solid patterns during synthesis is the key to controlling the manufacture of advanced materials from the bottom-up. The new discoveries generated by this program will be integrated into problem-based learning units for underrepresented middle school students, in partnership with the Detroit Area Pre-College Engineering Program (DAPCEP). The PI will assess the impact of these activities using annual and multi-year surveys distributed through the DAPCEP organization.

NON-TECHNICAL SUMMARY for Assistant Professor John Heron: “Understanding disorder, defects, and dielectric properties of entropy-stabilized oxides.”

The discovery and development of new materials underlies technological revolutions in microelectronics. Recently, a new materials field has emerged that harnesses large chemical and structural disorder to its advantage. This project will use atomic-scale engineering of structural and chemical disorder to discover and understand these new materials to achieve unprecedented functionalities. This project aims to leverage state-of-the-art film deposition with in-situ structural characterization and atomic-to-micron scale imaging techniques to understand the stabilization of structurally and chemically disordered multicomponent oxides, their complex structure, and the ways disorder induces novel physical properties. The results of this research are anticipated to provide new insights toward realizing new oxide materials and disorder-property relationships. Students in this project are receiving professional training in materials synthesis and the measurement of structural and dielectric properties of materials. Upon graduation, students are qualified for employment in academia and industrial fields - especially those related to microelectronics. This research is integrated with educational activities to engage pre-college students and establish a new pedagogy for physical science classes taught at the high school level. Curriculum components are being developed to introduce scientific practices and atomic-to-macroscopic scale thinking into the high-school classroom using the dielectric properties and applications of ceramics. The effort is bringing teachers together to receive training to integrate these new components into their teaching. The impact and merit of these activities is being assessed using biannual surveys and in-person interviews. 


NON-TECHNICAL SUMMARY for Assistant Professor Liang Qi: “First-Principles Predictions of Solute Effects on Defect Stability and Mobility in Advanced Alloys.” 

This CAREER award supports research and education activities in developing and applying computational methods for understanding the behavior of crystalline defects in metal alloys, which are metallic materials composed by more than one chemical element. Atoms in metals and alloys are arranged in crystal structures with almost perfect periodic patterns, but these structures still contain a small number of imperfections or "defects", variations from perfect periodicity. Many mechanical and physical properties depend on how defects are generated and move under the influences of alloying elements, or solutes, in crystal structures. For example, the strength and ductility of metals and alloys are usually controlled by a type of defect called dislocations, and some solute atoms can slow down or speed up dislocation motions to make alloys stronger and more brittle, or softer and more ductile. 

This project will focus on defects in advanced alloys based on certain transition-metal elements, such as tungsten, molybdenum, titanium, and zirconium. These alloys can have excellent mechanical properties at high temperatures and are critical for many energy, transport, and aerospace applications, such as structural components of nuclear reactors, turbine engines and electric generators. To develop these advanced alloys with enhanced performance would require the understanding of solute effects on defect behaviors and the corresponding variations of mechanical properties.

The objective of this project is to develop and apply computational methods to predict how solute atoms affect the stability and motion mechanisms of defects in advanced transition-metal alloys. Conventionally, accurate quantum mechanical calculations are applied to study metals and alloys in perfect crystal structures or containing simplified defect structures, but defect behaviors in realistic alloys depend on the evolution of complex structures on the nanoscale and mesoscale, lengths comparable with one-thousandth of a millimeter. The PI aims to discover intrinsic, universal and quantitative mechanisms that determine defect-solute interactions based on analyses from quantum mechanical calculations. Using these results, the PI will develop the models to predict the solute effects on defect behavior and mechanical properties by bridging the knowledge gaps between electronic, atomistic and mesoscale levels. The research will provide generalized models, computational methods, software tools, and an open access data repository for both the scientific and industrial communities to speed up the development of novel advanced alloys in large compositional space. 

The PI also proposes educational and outreach activities by integration of research and innovative teaching methods. The PI plans to apply virtual reality techniques in teaching complex crystal and defect structures to undergraduates, and to utilize the tools of computational materials science in teaching alloy designs to graduate students. Proposed outreach activities include the education of K-12 students with a diverse background on the topics of crystal structures and thermodynamics based on their interest and familiar subjects such as food processing to increase the public awareness of materials science and engineering. The PI will also participate in the high-school research projects by the Center for Engineering Diversity and Outreach at University of Michigan. All education modules based on virtual reality and simulation tools will also be shared through the public data repository.