Titanium alloys are highly prized in the aerospace and automotive industries because they are very strong, lightweight materials, but engineers are always looking for ways to manufacture even stronger, more flexible versions.

Mechanical Engineering Assistant Professor Lei Cao and her team are going about it by looking at defects and fine structures within titanium alloys, which can significantly affect the strength and pliability of the alloys.

This summer, Cao will begin research in this area funded by a National Science Foundation (NSF) CAREER award. The NSF’s Faculty Early Career Development Program (CAREER) is the agency’s most prestigious award in support of early-career faculty. Cao’s award of $554,915 over five years was announced in December 2022.

“This award brings visibility and honor to the Mechanical Engineering Department and keeps a tradition of at least one CAREER award in the department every year, which speaks to the quality of the Mechanical Engineering faculty and Dr. Cao in particular,” Professor Petros Voulgaris, Mechanical Engineering Department chair, said.

Cao’s project, “Fundamental investigation of twin boundary engineering through cyclic cross-phase-boundary thermomechanical processing,” involves developing computer models that can predict how fine structures within titanium alloys change under heat and pressure. The computer models can connect atomic-level material processes to design macroscopic (visible to the naked eye) material properties by rationally designing small-scale structures.

This work has the potential to improve the production of titanium alloys, add to the academic knowledge of microstructure processes in titanium alloys and support the next generation of mechanical engineers. It also aligns with the College of Engineering’s focus on resilient supply chains, lithium and critical materials.

“We are so proud of Dr. Cao’s achievement,” Engineering Dean Erick Jones said. “Her work is exemplary and highlights some of the top-notch research the College of Engineering is doing in the area of resilient supply chains, lithium and critical materials.”

Cao’s award is the sixth CAREER award won by College of Engineering faculty in 2022.

‘A great opportunity’

Pure titanium is strong and corrosive-resistant, but when combined with other metals (making it a titanium alloy), it takes on the greater flexibility of the metal with which it was combined. Titanium alloys — strong and flexible — have many industrial applications, but Cao explains that there’s room for improvement.

“It is well-known by researchers in our area that the mechanical properties of titanium alloys are significantly affected by the defects and other fine structures present in the material, which are challenging to predict or design,” she said.

Cao and her team have been investigating the material physics of titanium and similar metals, such as magnesium, for the past six years. The group’s recent work, published in Acta Materialia, revealed significant dependence of fine structure formation in titanium on the mechanical and thermal loadings applied to the material.

“This inspired me to propose this CAREER project to further explore the details, because we do not want to miss this great opportunity to advance the manufacturing of titanium alloys,” she said. 

Cao credits the University’s Pronghorn high-performing computing system with playing a critical role in her research.

Academic benefits

In addition to benefitting industry, Cao’s work has the potential to add to the body of knowledge on titanium alloys. Specifically, Cao says the computer models she and her team are developing for their project can be used by other researchers to better understand microstructure processes in titanium alloys.

“This CAREER project will be a critical step for me to achieve my long-term career goals to control mechanical properties of industry-critical materials by engineering fundamental materials physics,” she said.

Cao added that the project also will advance another of her goals: preparing students in Science, Technology, Engineering and Math (STEM) for the workforce by with integrated skills in mechanical engineering and materials science.