  Metals in amorphous state are promising for the use as structural materials
due to their superior properties related to the absence of grain boundaries and
dislocations.Obtaining the amorphous state requires quenching with a high
cooling rate.In conventional technologies,this is the reason for a considerable
size limitation hindering application of amorphous alloys.Additive
manufacturing (AM) is free of the size limitation.The so-called bulk metallic
glass (BMG) alloys have extremely low critical cooling rates and can be used in
AM. Recent studies on AM from Zr-based BMGs by selective laser melting(SLM)has
proved the possibility of attaining the amorphous state and revealed partial
crystallization to be the principal drawback of this process.The present work
aims to analyze the conditions for partial crystallization and try to control
it by optimizing the process parameters.A comprehensive parametric analysis is
accomplished in single-track SLM experiments with Zr-based BMG alloy Vit
106.The observed microstructures are related to the temperature fields and
thermal cycles estimated by an analytic heat-transfer model in the laser-impact
zone.In the cross section of a laser track,a central bright domain is
identified as the remelted zone.An annular darker crystallization zone
encircles the remelted zone.The model fits the experimentally obtained
dependencies of the remelted zone size versus laser power and scanning speed.It
seems that primary crystalline inclusions existing in the substrate before
laser processing dissolve at the laser melting.The mean cooling rate in the
remelted zone is much greater than the critical cooling
rate.Therefore,homogeneous nucleation isn't expected.Nevertheless,the
theoretically estimated crystallization times are sufficient for a considerable
crystal growth in the heat-affected zone where primary crystalline inclusions
and nuclei are not completely dissolved
