The effect of synthesis of the starting powders on the properties of Cu-Ti-TiB2 alloy obtained by laser melting

A comparison was made between layer-by-layer laser melting (LM) of two types of feedstock powders: (1) elemental powder blend and (2) mechanically alloyed powder. LM was done by Nd:YAG laser at 1064 nm (max. average power 100 W) in argon ambience. Samples synthesized were Cu-Ti-TiB2 rectangular tracks (20x6x1 mm), and input parameters of the process: powder layer thickness 100-250 µm, hatch spacing 1 mm, pulse length 4 ms, energy 4 J, pulse repetition rate 20 Hz. Part of the samples was heat-treated in argon at 900 °C, 10 h. Structural characterization of the samples was done using light microscope and scanning electron microscope (SEM). Chemical analysis of the as-obtained laser melted samples was done by inductively coupled plasma-atomic emission spectrometry (ICP-AES). It was established that the microstructure of LM samples was comprised of Cu-Ti and Cu-B solid regions, and in situ formed microparticles of primary TiB2. Only after high-temperature thermal treatment has the secondary TiB2 occurred. Tensile tests showed much higher strengthening in heat-treated samples with mechanically alloyed powder as starting material, where the formation of secondary TiB2 nanoparticles was considerable