Microstructural evolution in laser deposited compositionally graded α/β titanium-vanadium alloys

A graded binary Titanium-Vanadium alloy, has been deposited using the laser engineered net-shaping (LENS(TM)) process from a blend of elemental Ti and V powders. A compositional gradient in the alloy, from elemental Ti to Ti-25at%V, has been achieved within a length of similar to25 mm. Subsequent to deposition, longitudinal sections of the deposit have been characterized in detail using scanning and transmission electron microscopy. Though the phases across the graded alloy correspond to those typically observed in alp Ti alloys, the scale and morphology of the microstructural features varies substantially with composition. Several phase transformations, namely, beta-->Widmanstatten alpha, beta-->omega and martensitic beta-->hexagonal alpha', are encountered in the graded alloy sample during LENS(TM) deposition. The ability to achieve such substantial changes in composition across rather limited lengths make such graded alloys highly attractive candidates for investigating the influence of systematic compositional changes on phase transformations and concurrent microstructural evolution in these alloys. (C) 2003 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.