Microstructure Study of Direct Laser Fabricated Compositionally Graded Ti alloys UsingSimultaneous Feed of Powder and Wire

摘要

A compositionally graded material has been fabricatedusing Direct Laser Fabrication. Two types of feedstockwere fed simultaneously into the laser focal point, aburn resistant (BurTi) alloy Ti-25V-15Cr-2Al-0.2Cpowder and a Ti-6Al-4V wire. The local compositionof the alloy was changed by altering the ratio ofpowder to wire by varying the feed rate of the powderwhilst maintaining a fixed feed rate of wire-feed. Forthe range of compositions between about 20% and100% BurTi only beta was observed and thecomposition and lattice parameter variedmonotonically. The grain size was found to be muchfiner in these functionally graded samples than in laserfabricated Ti64. Some samples were made using thewire-feed alone, where it was found that themicrostructure is different from that found when usingpowder feed alone. The results are discussed in termsof the power requirements for laser fabrication ofpowder and wire samples.