J-integral evaluation of cold worked and aged TiNbSn alloys as a function of alloy content

Abstract

The present study evaluates the J-integral resulting from cold rolling and aging treatments applied to TiNbSn alloys comprising different contents of Nb (35% and 42%) and Sn (0% and 2.5%). The alloys were arc melted, homogenized, solution heat treated, cold-rolled and aged at 400 °C during different aging times. A set of characterization tests, including microstructural, scanning electron microscopy, work hardening coefficients and fracture analysis were performed. The cold worked alloys with the highest Nb content showed the highest toughness. The addition of Nb in these alloys is beneficial for toughness since Nb stabilizes the β phase. In alloys with lower Nb content, cold forming causes a greater amount of α" and this disfavors toughness. Aging caused a reduction in the alloys' toughness, since the formation of precipitates in aging causes shallower and smaller dimples in the fracture, corroborating to a lower toughness.