Effects of shock loading on Young's modulus and activation energy of recovery in 1018 steel

Abstract

Synthesis of the new (disordered) compound CaFe(CO3)2 has been achieved with the use of Fe-substituted CaCO3(Cc ss) + Ca-substituted FeCO3(Sid ss) as starting materials, and high CO2 pressures. High pressure (20–30 kbar) is needed to stabilize FeCO3 to sufficiently high temperatures for disordered CaFe(CO3)2 to form. Experiments provide reversed compositions of coexisting disordered phases in the CaFe join and locate the solvus temperature for CaFe(C)3)2 between 815 and 845°C at 30 kbars. Calculated phase relations predict that the stability of ordered CaFe(CO3)2 is limited to T < ∼450°C by the breakdown to Cc ss + Sid ss. A comparison of the unit-cell volume measured for disordered CaFe(CO3)2 vs. that estimated for ordered CaFe(CO3)2 suggests that increasing pressure stabilizes the disordered phase.