Elastic stiffness and damping measurements in titanium alloys using atomic force acoustic microscopy

Atomic force acoustic microscopy (AFAM) has been used to study the distribution of elastic stiffness and damping properties across different phases, such as α & β phases in a β titanium alloy (Ti10V4.5Fe1.5Al) and α, β and α′ phases in an α + β alloy (Ti6Al4V). Contact-resonance spectra were obtained with a 100 nm spatial resolution in various specimens of the two titanium alloys heat-treated at different temperatures. The study indicates that the metastable β phase has the minimum modulus and maximum damping followed by α′ and α-phases. Employing the rule of mixtures, the average modulus measured by AFAM was then compared with the modulus obtained by ultrasonic velocity measurements. The error in the average modulus values obtained by both techniques is discussed.