Effect of Hypoeutectic Boron Additions on the Grain Size and Mechanical Properties of Ti-6Al-4V Manufactured with Powder Bed Electron Beam Additive Manufacturing

Microstructure and Porosity of Laser Welds in Cast Ti-6Al-4V with Addition of Boron

“…[4][5][6] Recent work [7][8][9] has indicated that addition of a small amount of boron to a titanium alloy can render a significantly finer microstructure in cast titanium alloys. Similar observations have been reported [10][11][12] in additive manufacturing where boron addition has been shown to refine the otherwise typically coarse columnar prior-b grain morphology. Reconstruction of the b grains, using the electron back scatter diffraction data of a phase, has proven to be a powerful method to characterize prior-b grain structure in titanium alloys.…”

“…This microstructural refinement with boron addition agrees well with findings of others in cast Ti-64 [7][8][9]16] and in additive manufacturing. [9,11] It has been well established that trace boron addition refines the prior-b grain structure in cast titanium alloys. The hypothesis by Tamiriskandala et al [8] suggests that b-grain refinement is based on the growth restriction provided by boron because a boron-rich layer is formed around the solidifying b-grain.…”

“…[7,8] The formation of TiB particles has been observed in castings with slow cooling rate [6,7] as well as in additive manufacturing with high cooling rate. [9,11] In cast material, the TiB particles are mainly located at the prior-b grain boundaries. In the FZ of welds in cast boron-modified Ti-64 alloys, the TiB needles are typically clustered in the interdendritic regions and here form stripes throughout the FZ.…”

Embedding boron into Ti powder for direct laser deposited titanium matrix composite: Microstructure evolution and the role of nano-TiB network structure

“…Recently, several studies reported a new approach to prepare raw powder [24,25]. Li et al [24] designed an in-situ nano-TiB2 decorated AlSi10Mg powder by gas atomization for selective laser melting and fully dense nano-TiB2 decorated AlSi10Mg alloy was successfully fabricated with high fracture strength and ductility.…”

“…Li et al [24] designed an in-situ nano-TiB2 decorated AlSi10Mg powder by gas atomization for selective laser melting and fully dense nano-TiB2 decorated AlSi10Mg alloy was successfully fabricated with high fracture strength and ductility. Mahbooba et al [25] pre-alloyed Ti-6Al-4V powder with boron to fabricate bulk samples via electron beam additive manufacturing, the micro-hardness and strength of the fabricated samples were sharply enhanced by increasing boron element which also induced a significant refinement of α grains. As investigated in previous works, the composite powder produced from prefabricated composite ingots could avoid the shortcomings of mechanical blending and had a positive effect on their performance.…”