The need for stronger and lighter materials is greater than ever before. Whether it is polymer or metal, the Taub lab works to establish lasting change in the structural and functional material sectors
Metal matrix nanocomposites via in situ synthesis
The addition of ceramic nanoparticles to base metal alloys has demonstrated increased mechanical properties at both ambient and elevated temperatures. However due to the nonwetting characteristics of ex situ fabricated composites, these materials have not found widespread use in the industry. By synthesizing the reinforcement in the molten metal by salt-based flux reaction, these incorporation issues can be bypassed completely. Understanding the reaction pathways and solidifcation interactions of these particles will lead to optimally reinforced materials that could drastically increase automotive and aerospace vehicle performance.
Solidification Processing via Electric Current
Metal alloys in the automotive and aerospace industry are commonly processed either while molten or after casting to achieve a targeted performance metric for the end product. In order to provide the tools to further tune the product microstructure, we are exploring solidification of metal alloys and metal matrix composites when processed with a low power electric current. Although the effects of high current amplitudes have been established and studied extensively for the past few decades, a mechanistic explanation has not been established that accounts for the microstructural changes that occur at low current processing conditions. Our goal is to determine a unified physical understanding of electric current modification when applied during solidificication. Understanding this relationship between electric current processing and final cast microstructure will lead to the advanced manufacturing processes that could increase material properties at reduced costs
Formation of banded microstructures
Directional Solidification allows control of the thermal gradient and the interfacial velocity, two crucial parameters for the solid-liquid interface stability. Under certain alloy concentrations coupled with the aforementioned parameters, can give rise to banded microstructures. For MMCs and monotectic alloys, we encounter a periodic transition between particle rich and particle deficient regions. Although there exists a proposed theory for banded microstructures in off-eutectic alloys, this proposes a constant band spacing of primary phase and eutectic throughout the sample, which we don’t observe experimentally in MMCs and monotectic alloys. We envision controlling the band spacing of these microstructures to enhance the mechanical properties and widen the applicability of Metal Matrix Composites in industry.
Design of Electromagnetic Wave Absorbers
In order to ensure the safe and reliable operation of modern electronic equipment, electromagnetic (EM) interference must be mitigated. Instead of reflecting signals using highly conductive metals, which can redirect interference to other sensitive equipment, EM absorbers allow the signal energy to dissipate as heat. We accomplish this through two ways: careful tailoring of the electric and magnetic properties of polymer nanocomposites enables dielectric, conductive, and magnetic losses; and design of periodic geometries (i.e. metastructures) allows for resonance with the incident wave.
We employ advanced modeling techniques and Monte Carlo simulations to optimize resonant metastructures at target frequencies to both maximize signal absorption and broaden the absorption bandwidth. By validating the model with experimental testing, our work aims to develop efficient, lightweight, and cost-effective EM absorbers that meet the growing demands of the electronics, aerospace, defense, and medical industries.
Nanocomposites for Lightweight Conductors
Using fibrous network matrices has been shown to reduce the critical volume fraction of filler components to achieve percolation in nanocomposite materials. By implementing a fibrous polymer matrix material, and attaching conducting nanoscale elements within the matrix material, electrical performance can be achieved while maintaining a low amount of heavy constituents. This results in a low-density conductor material which can be implemented in electronic systems in the automotive and aerospace sectors resulting in improved fuel efficiency and reduced greenhouse gas emissions.
Rapid estimation of multicomponent phase diagrams
Since Yeh and Cantor’s papers in the early 2000s, high entropy alloys (HEAs) have emerged as a highly-researched new class of alloys for high strength and high temperature applications. Due to their innate chemical complexity, producing reliable thermodynamic modeling has proven to be a major challenge for these alloys. By leveraging high throughput liquidus measurements coupled with energy calculations from density functional theory (DFT), the ability to rapidly estimate the phase diagrams for these systems can finally be realized, clearing the path for improved compositional design.
Natural fiber composites
Organic-based materials provide a pathway to carbon-neutral or even carbon-negative structural reinforcement by strengthening the plant-based fibers used in polymer composites. Flax, hemp, and bamboo fibers can be reinforced through the integration of nanoparticles like nanocellulose, carbon nanotubes and graphene during plant growth to enhance the strength of the fiber structure. This natural fiber composite research aims to improve mechanical performance and contribute to sustainability in structural material systems
Incremental sheet forming
This method of sheet manufacturing has devloped in recent years as an unique manufacturing method that offers improved design flexibility over traditional sheet forming processes. The introduction of ultrasonic vibrations leads to a formation force reductions via the acoustoplastic effect (APE). Heat assisted incremental sheet forming utilizing large amplitude electric currents has been found to enhance local material formability in sheets that are resistant to deformation at room temperature heating of the sheet.