In-situ Studies of Strain Rate Effects on Phase Transformations and Microstructural Evolution in Beta-Titanium and Multi-Principal Element Alloys
Abstract
Transformation-Induced Plasticity (TRIP) and Twinning-Induced Plasticity (TWIP) are being exploited in steel microstructural design to develop lightweight, advanced high strength steel (AHSS) products for optimum crash performance and are revolutionizing the transportation sector. TRIP/TWIP behavior is known to be beneficial to strain hardening in steels, yet the study of these mechanisms in other metallic alloys is largely unexplored, especially for the design of blast resistance, where TRIP metallic alloys have been shown to resist adiabatic shear band formation through local strain hardening. Although metastable beta-titanium (beta-Ti) and Multi- Principal Element (MPE) alloys have the potential to exhibit TRIP/TWIP, little to no work has been done to exploit this novel behavior or design alloys for targeted performance. To date, high strain-rate data for beta-Ti and MPE alloys, particularly in tension, are virtually nonexistent. How alloying impacts microstructural development and what microstructural characteristicscontrol TRIP/TWIP behavior during quasi-static and dynamic deformation is unknown. Multiscale, in-situ characterization is affording new opportunities to study microstructural evolution and deformation mechanisms at high strain rates and under dynamic loading conditions, including under non-ambient pressures. This new knowledge is needed to design lightweight metallic alloys for blast resistance. Here we will perform state-of-the-art microstructural characterization and in-situ imaging and diffraction of microstructural evolutionin metastable beta-Ti and MPE alloys from the nanoscale to macroscale during quasi-static and dynamic testing to fundamentally understand TRIP/TWIP behavior to design metallic alloys for blast resistance.Specifically, we will answer the following scientific questions:1. How does alloying impact microstructural development and what characteristics (e.g. phases, grain size, morphology, texture, etc.) control TRIP/TWIP behavior in metastable beta-Ti and MPE alloys?2. How does deformation in extreme environments (strain rate, temperature, strain state, pressure) affect microstructural evolution and TRIP/TWIP behavior?3. Can we use fundamental knowledge of TRIP/TWIP to design metastable beta-Ti and MPE alloys and microstructures with tailored phase transformations and deformation mechanisms to optimize blast resistance?This deep understanding will inform alloy and process design by Integrated Computational Materials Engineering (ICME) toward the creation of blast resistant structural metallic alloys for lightweight armor with superior warfighter protection, operational endurance, and maneuverability. This work is in alignment with the interests of the Cellular Materials Program of the Naval Materials Division in materials under dynamic deformation processes and thedesign of blast and fragmentation resistant structures.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 27, 2018
- Source ID
- N000141812567
Entities
People
- Amy Clarke
Organizations
- Colorado School of Mines
- Office of Naval Research
- United States Navy