probing the strengh of iron at ultra-high pressures and strain rates

Department: Mechanical & Aerospace Engineering
Faculty Advisor(s): Marc A. Meyers

Primary Student
Name: Joshua Stephan Pelz
Phone: 503-729-4021
Grad Year: 2021

Iron is the major component of the Earth?s core. Determining its strength at extreme conditions is crucial to understanding core rheology, geophysical observations, and the origin of the geodynamo. Iron strength directly has a direct influence on the timeline of the Earth's core formation dynamics, an area of geophysical science that is not well understood. Seismological measurements of the Earth show anisotropy in sound velocity characteristics; velocities are systematically larger by 3-4% along Earth's rotational axis. This peculiar observation suggests that iron crystallites in the inner core are highly textured (oriented in a preferential directions). Preferred orientations of these crystallites would greatly influence iron's bulk strength at these extreme conditions and would have major consequences for core rheology. In order to advance the fundamental science of the strength and plastic flow of iron under extreme loading conditions, experiments have been scheduled at the National Ignition Facility (NIF). NIF is the most powerful laser facility in the world; capable of generating 1.85MJ during only 10-20ns. This uniquely allows iron strength measurements at pressures above 350 GPa (3.5 Mbar), temperatures above 4000 K, and strain rates of 10^7 to 10^8 s^-1; simulating earth core conditions. Iron will be tested at these conditions, and strength data will be calculated through collected Rayleigh-Taylor (RT) growth data. Probing the ultimate strength of materials is critical in advancing materials science knowledge at the extremes and improving the design of next generation materials to fulfill applications in extreme loading environments.

Industry Application Area(s)
Aerospace, Defense, Security | Energy/Clean technology | Materials

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