The elastic stiffnesses of Fe-Ni-C martensites

Abstract

An ultrasonic interferometric technique was used to measure the longitudinal and transverse sound velocities in untempered carbon-nickel martensites. An increase of about 0·11 × 10⁵ cm/sec per atomic per cent carbon was observed for both velocities (in the presence of decreasing nickel contents). The mass densities of the martensites were also measured to allow calculation of the elastic moduli. Even with corrections applied for decreasing nickel contents both the shear and bulk moduli were found to increase with the carbon content, especially the shear modulus. This provides evidence that carbon increases the atomic cohesion within martensite.