Synthesis of Fe-Al-Ti Based Intermetallics with the Use of Laser Engineered Net Shaping (LENS)

Abstract

The Laser Engineered Net Shaping (LENS) technique was combined with direct synthesis to fabricate L21-ordered Fe-Al-Ti based intermetallic alloys. It was found that ternary Fe-Al-Ti alloys can be synthesized using the LENS technique from a feedstock composed of a pre-alloyed Fe-Al powder and elemental Ti powder. The obtained average compositions of the ternary alloys after the laser deposition and subsequent annealing were quite close to the nominal compositions, but the distributions of the elements in the annealed samples recorded over a large area were inhomogeneous. No traces of pure Ti were observed in the deposited alloys. Macroscopic cracking and porosity were observed in all investigated alloys. The amount of porosity in the samples was less than 1.2 vol. %. It seems that the porosity originates from the porous pre-alloyed Fe-Al powders. Single-phase (L21), two-phase (L21-C14) and multiphase (L21-A2-C14) Fe-Al-Ti intermetallic alloys were obtained from the direct laser synthesis and annealing process. The most prominent feature of the ternary Fe-Al-Ti intermetallics synthesized by the LENS method is their fine-grained structure. The grain size is in the range of 3–5 μm, indicating grain refinement effect through the highly rapid cooling of the LENS process. The Fe-Al-Ti alloys synthesized by LENS and annealed at 1000 °C in the single-phase B2 region were prone to an essential grain growth. In contrast, the alloys annealed at 1000 °C in the two-phase L21-C14 region exhibited almost constant grain size values after the high-temperature annealing.

Laser metal deposition and selective laser melting of Fe–28 at.% Al

“…14 Layer-by-layer production of powder stacks and subsequent uniaxial pressing, 15 layer-by-layer 3D cladding, 16 and laser engineered net shaping (LENS) 17 have been explored for the production of chemically graded Fe-Al samples. The only reports on ALM of Fe 3 Al-based alloys are on precipitation hardened Fe-30Al-0.35Zr-0.1B (in at.%) 18 and Fe-Al-Ti alloys 19 by LENS.…”

Direct Synthesis of Fe-Al Alloys from Elemental Powders Using Laser Engineered Net Shaping

“…The machine that was used in this particular experiment was custom made on the base of MR-7 (Optomec, Albuquerque, NM, USA) and it provides the opportunity to compose various powder mixtures delivered from up to four powder feeders at the same time. The software and hardware is configured in the way that multi-material samples, even sample libraries and gradient materials [67,[74][75][76], can be built while using elemental powders or premixed powders up to user's choice.This feature provides the most significant difference between LENS process and the most widely used powder bed type methods, where the layer of the powder is spread over the table, then remelted, lowered, and the process is repeated. The system is equipped with a fiber laser with a maximum power of 500W and a thermal imager system for an investigation of the cooling rates withing the molten metal pool (if necessary).…”

Microstructures and Properties of Laser Cladding Al-TiC-CeO2 Composite Coatings

“…Based on the current level of technology, a 200-μm-thick Al cladding coating is expected to last for more than 30 years in the splash area for steel structures. Therefore, the preparation of laser cladding Al coatings has become a hot topic for research in the field of long-term heavy corrosion protection [ 18 , 19 ]. At present, Yang et al [ 20 ] have prepared an Al-TiC in situ composite coating fabricated by low power pulsed laser cladding on AZ91D magnesium alloy.…”