THE MAJOR SCIENTIFIC GOAL OF THIS PROJECT IS TO EXPLORE THE PHASE STABILITY OF FE3C AT CONDITIONS OF PLANETARY CORES, INCLUDING THE CRYSTAL STRUCTURE AND ANY PHASE TRANSFORMATIONS AT PRESSURES UP TO 600 GPA AND TEMPERATURES UP TO 5000 K. THE EXPERIMENTAL PROGRAM WILL UTILIZE DEVELOPMENTS IN X-RAY DIFFRACTION TO CHARACTERIZE MATERIAL RESPONSE AT THE ATOMIC LEVEL UNDER BOTH RAMP AND SHOCK LOADING. DIFFRACTION WILL BE COMBINED WITH VELOCIMETRY MEASUREMENTS TO CHARACTERIZE THE CONTINUUM EQUATION OF STATE OR IRON CARBIDE. THIS PROJECT WILL DELIVER NEW FUNDAMENTAL INFORMATION ON THE FE-C PHASE DIAGRAM AT EXTREME PRESSURE-TEMPERATURE CONDITIONS. EXPERIMENTS WILL BE CARRIED OUT AT STATE-OF-THE-ART LASER-SHOCK FACILITIES INCLUDING THE DYNAMIC COMPRESSION SECTOR (DCS) AT ARGONNE NATIONAL LABORATORY AND THE OMEGA LASER FACILITY AT THE LABORATORY FOR LASER ENERGETICS (LLE). THEY WILL ALSO SEEK TIME TO CARRY OUT PULSED-POWER EXPERIMENTS AT SANDIA’S Z MACHINE. TO GUIDE THE EXPERIMENTAL EFFORT, A THEORETICAL/SIMULATION THRUST WILL PERFORM QUANTUM ACCURATE CLASSICAL MOLECULAR DYNAMICS SIMULATIONS TO PREDICT THE EQUATION OF STATE, PHASE DIAGRAMS, AND COMPRESSION PATHWAYS, PROVIDING ATOMIC-SCALE INSIGHT INTO PHASE TRANSFORMATIONS OF IRON CARBIDE UNDER DYNAMIC COMPRESSION.