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The control of solidification microstructure is critical to successful laser processing of single-crystal (SX) nickel-base superalloys and a practical tool for the microstructural control is processing–microstructure maps. However, the maps presented in literature do not consider the effects of powder feeding during laser additive manufacturing (LAM) of SX superalloys. This paper therefore presents a simple and feasible strategy to deal with the effects of powder feeding and to extend the combined numerical model used to calculate processing–microstructure maps. A characteristic ratio of epitaxial SX growth was defined to quantitatively compare the final solidification microstructure. Resulting processing–microstructure maps can estimate the influence of most processing variables, especially powder feeding rate, on the extent of epitaxial SX growth and the position of columnar-to-equiaxed transition. Using the processing parameters selected according to these processing–microstructure maps, a multi-layer SX deposit with fine dendrites was successfully fabricated by LAM. This successful SX LAM indicates that these new processing–microstructure maps involving powder feeding are reliable and useful because they can determine proper processing windows for LAM of SX superalloys and further advance the understanding of the processing–microstructure relationship in powder-feeding LAM process. [ABSTRACT FROM AUTHOR]

Abstract: The compositional variation and the microstructural evolution in laser additive manufactured Ti/Ti–6Al–2Zr–1Mo–1V graded structural material were investigated. An anomalous compositional variation and its good correlation with hardness were found. Although, during the forming process, the ratio of Ti–6Al–2Zr–1Mo–1V in feeded powders abruptly changes from 0% to 100%, all the elements exhibit a gradual variation, which is preferred to a graded material because such gradient change can decrease the discontinuity of its microstructures and properties and can remarkably reduce the costs due to the simplified manufacturing process and the rational distribution of materials. [Copyright &y& Elsevier]

The mechanical behavior of commercial purity Ti (CP-Ti)/Ti–6Al–2Zr–1Mo–1V structurally graded materials (SGMs) fabricated by laser additive manufacturing was investigated via uniaxial tensile experiments. Although the strength of all SGM specimens is higher than that of the monolithic CP-Ti specimens, only the SGM specimen of Ø10mm gauge diameter with bulky α-grains exhibits excellent plasticity comparable to the CP-Ti specimen under the same conditions. The SGM presents a potential for use as load-bearing components due to its good strength–ductility balance. [ABSTRACT FROM AUTHOR]

High density, high strength and high susceptibility to adiabatic shear banding (ASB) have always been pursued by tungsten heavy alloys (WHAs) for kinetic energy armor-piercing projectiles. To meet the demand, this work reported a novel tungsten heavy alloy with high-density L1 2 precipitation-strengthened Co9Al9W binder (WCAW). WCAWs were prepared by liquid phase sintering (LPS) and laser ultrashort-time liquid phase sintering (LULPS) respectively. Experimental results show that LULPS technique with large molten pool convection and rapid solidification can produce WCAWs with uniform W distribution, low W-W contiguity and fine W particles. Conversely, W particles in LPS WCAWs were excessively connected and segregated. The uniform distribution, low W-W contiguity and fine W particles enable LULPS WCAW to exhibit better mechanical properties. The ultimate compressive strength of the LULPS WCAWs is ∼2442 MPa, 16.4 % higher than that of the LPS WCAWs. As well, the dynamic yield strength of LULPS WCAWs is high, which is ∼2281 MPa and 37.4 % higher than that of LPS WCAWs. • A novel tungsten heavy alloy with Co9Al9W binder (WCAW) was developed. • WCAWs with high W content of 93 wt% were prepared by two different techniques (LPS and LULPS). • W particles in LULPS WCAWs were fine and distributed uniformly in γ matrix. • LULPS WCAWs showed much higher compressive strength and dynamic strength than LPS WCAWs. [ABSTRACT FROM AUTHOR]