In-Situ Micro-Mechanical System for Testing of Advanced Materials under Extreme Conditions of Temperature, Strain-Rate and Applied Stress
Abstract
We request support for expanding the capabilities of the Alemnis in-situ micro-me-chanical system to include extreme conditions of temperature (-150 to 1000 oC), a wide range of applied strain-rates (10-4 to 104/s) and high applied stresses. In the current materials and mechanical research environment, researchers traditionally examine mechanical properties of microscale volume using indentation tests which are conducted at quasistatic rates (i.e. at strain rates in the range of 10-5 to 10-2 /s) and under ambient conditions (s room temperature). How-ever, the dynamic properties of the local regions of interest remain unexplored, especially at elevated/cryogenic temperatures and applied stresses. The current proposal suggests an excit-ing transformative solution, where by expanding the capabilities of our current Alemnis in-situ SEM system we will be able to evaluate local material response over wide extremes of temper-ature, strain rates and loading conditions. The Alemnis SEM system was chosen as the best combination of system performance, modular design and cost target. The instrument is specifically designed to leverage the advanced imag-ing capabilities of scanning electron microscopes, and integrated focused ion beamand/or elec-tron backscatter diffraction systems, which allows us to capture the local microstructural evo-lution during the course of deformation. This is a unique system (and different from other man-ufacturers) in that it is a depth-controlled system. Most indentation systems are load controlled. Being depth controlled it will allow us to achieve high strain rate measurements of up to 104/s strain rates (thus covering an impressive 9 orders of magnitude of strain rates). Such high strain rate measurements can be used to mimic ballistic tests at the micron scale, perform strain rate jump tests, as well as measure activation energies and activation volumes from sub-micrometer sized specimens, which can be highly instrumental in understanding their deformation mecha-nisms especially at elevated and cryogenic temperatures. In addition to the traditional indenta-tion mode, this instrument will also allow testing of varied loading geometries, such as micro-compression, micro-(cantilever and 3-point) bending, micro tension, low cycle fatigue, na-noscale wear tests, etc. No other manufacturer (US or non-US) offers this range of capabilities. A micro-mechanical system capable of extreme conditions is needed to pursue research in sev-eral key areas of interest to the department of Defense, and the Army in particular, where it will significantly expand the capabilities available at local (sub-µm to nm) length scales: (1) mechanistic design of hierarchical multilayered nanocomposites for enhanced strength and toughness; (2) statistical investigation of damage formation in polycrystalline metallic materi-als under dynamic loading conditions; (3) additively manufactured shape memory alloys for on demand shape change and damage mitigation; (4) investigating the local stricture-property correlations in alloys for cryogenic (space) applications; and (5) biomechanics of hierarchi-cally-structured enamel in grinding dentitions. Collectively, this work Ð enabled by the ex-panded capabilities of the Alemnis system Ð will advance multidisciplinary research programs in science and engineering, which spans from structural engineering materials, energy and functional materials to nanostructured materials and natural biological materials. Additionally this system will help establish a research capability that is unique in the state as well as in the entire country, thus fostering an exclusive research-related education system at courses taught at Iowa State University. The proposed system will also significantly advance cross-discipli-nary collaborations with DoD and DoE laboratories such as the Army Research Lab, Ames and Los Alamos National Laboratories, especially in the fields of micro-mechanical testing and advanced manufactu
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 25, 2021
- Source ID
- W911NF2110042
Entities
People
- Siddhartha Pathak
Organizations
- Army Contracting Command
- Iowa State University
- United States Army