Achievement of ultimate values of the bulk and shear strengths of iron irradiated by femtosecond laser pulses

Abstract

Shock-wave phenomena generated by femtosecond laser pulses in submicron iron film samples have been studied by the interferometric method with the application of frequency-modulated diagnostics in the picosecond time range. The splitting of the shock wave into the elastic and plastic waves with a compression stress of up to 27.5 GPa behind the front of an elastic precursor has been detected. The corresponding maximum shear stress reaches 7.9 GPa, which is even somewhat higher than the calculated ideal shear strength. The measured spall strengths reach 20.3 GPa, which is also comparable to the calculated values of the ideal tensile strength.