Study of plastic deformation mechanisms in TA15 titanium alloy by combination of geometrically necessary and statistically-stored dislocations

This study combines geometrically necessary dislocation analysis and statistically-stored dislocation identification to investigate plastic deformation mechanisms in TA15 titanium alloy. Tensile tests were conducted up to different strains at room temperature. The slip lines were observed and identified using high resolution scanning electron microscopy. Geometrically necessary dislocations were calculated based on strain gradient theories. The statistically-stored dislocations were studied using transmission electron microscopy under two beam conditions. The results indicate that the ratio of 〈a〉-type geometrically necessary dislocation density to 〈c+a〉-type decreases from 5-8 to 1-3 with increasing strain from 0.8 % to 2.0 %. The 〈a〉type slip is the dominant deformation mechanism at the early stage of plastic deformation, whereas 〈c+a〉-slips become dominant with further increase in deformation strain.