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1	Microstructural Phase Evolution In Laser Deposited Compositionally Graded Titanium Chromium Alloys Thomas, Jonova 05 1900 (has links) A compositionally graded Ti-xCr (10≤x≤30 wt%) alloy has been fabricated using Laser Engineered Net Shaping (LENSTM) to study the microstructural phase evolution along a compositional gradient in both as-deposited and heat treated conditions (1000°C followed by furnace cooling or air cooling). The alloys were characterized by SEM BSE imaging, XRD, EBSD, TEM and micro-hardness measurements to determine processing-structure-property relations. For the as-deposited alloy, α-Ti, β-Ti, and TiCr2 (C15 Laves) phases exist in varying phase fractions, which were influential in determining hardness values. With the furnace cooled alloy, there was more homogeneous nucleation of α phase throughout the sample with a larger phase fraction of TiCr2 resulting in increased hardness values. When compared to the air cooled alloy, there was absence of wide scale nucleation of α phase and formation of ω phase within the β phase due to the quicker cooling from elevated temperature. At lower concentrations of Cr, the kinetics resulted in a diffusionless phase transformation of ω phase with increased hardness and a lower phase fraction of TiCr2. In contrast at higher Cr concentrations, α phase separation reaction occurs where the β phase is spinodally decomposed to Cr solute-lean β1 and solute-rich β2 resulting in reduced hardness. Laser Engineered Net Shaping Titanium alloys Microstructure evolution Material characterization SEM XRD EDS TEM EBSD Microhardness Titanium-Chromium Binary alloy Heat Treatment Phase transformation Compositional Gradient β stabilized Ti alloy. Titanium alloys -- Microstructure. Lasers in engineering. Chromium alloys -- Microstructure.

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Microstructural Phase Evolution In Laser Deposited Compositionally Graded Titanium Chromium Alloys