OPTICAL DIAGNOSTICS OF THE MELT POOL DURING SELECTIVE LASER MELTING OF VIT 106 ALLOY

Abstract

Bulk metallic glasses (BMG) are promising materials due to their mechanical properties. The main difficulty in obtaining products from BMG is the massive parts, since a high cooling rate is required to preserve amorphous state. The use of additive manufacturing will avoid the need to obtain massive billets by conventional methods. In addition, using selective laser melting (SLM) technology, the material is selectively fused and the cooling rate is sufficient to avoid crystallization in the material. However, despite the high cooling rates, crystal formation is possible in some processing modes. In order to avoid crystallization, it is necessary to better understand the processes occurring in the laser-processing zone. In this work, we visualize laser processing of metallic glass plates by a high-speed camera to estimate the size of the melt pool. The melting front of the melt pool is clearly observed, while it is not possible to identify the crystallization front on the video frames. Additional image processing helps to visualize the melt pool. Using a photo editor, adjacent frames are subtracted, which make it possible to determine the boundary of the melt pool by comparing frames. Using this method, we are able to estimate the location of the crystallization front, which allows us to estimate the size of the melt pool.