Two types of martensite morphologies have been obtained in zirconium and zirconium-niobium alloys containing up to 5.5 wt.% niobium. The massive martensite of pure zirconium and alloys containing less than 0.8 wt.% niobium, shows twin free martensite plates whereas the acicular martensite plates are internally twinned predominantly on {1011} planes. Other inhomogeneous shear systems like {101¯1} <1¯1¯23> slip and {112¯2}<1¯1¯23> twin have also been found to be operative. Evidences for additional inhomogeneous shear inside thick twin bands have also been found. Simultaneous occurrence of both (2¯112) twinning and (1¯101) slip along the common direction [21¯1¯3] provide another example of multiple shear inhomogeneous deformation. The habit plane determinations of these alloys indicate that the {334}β habit, already reported for pure zirconium, remains unaltered with the addition of niobium. This is to be expected because the principal lattice strains do not change appreciably with niobium addition.
This paper was originally published in Acta Metallurgica 19 (1971) Pages 1317 - 1326
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Control over the toughness and ductility of alloys