The critical role of heating rate in enabling the removal of surface oxide films during spark plasma sintering of Al-based bulk metallic glass powder

Metallic glass powder of Al86Ni6Y4.5Co2La1.5, prepared by nitrogen gas atomization, was consolidated into 10mm diameter bulk metallic glass (BMG) samples using spark plasma sintering (SPS). The use of a high heating rate is critical to ensure oxide-free, well-sintered clean interfaces between the powder particles and therefore desired mechanical properties, compared to oxide-enveloped, poorly-sintered interfaces that result from the use of a slow heating rate. The marked influence of heating rate is attributed to the surface-cleaning effect of SPS associated with the increased electrical discharge. •Direct evidence shows that SPS can remove surface oxide layers on metallic glass powder.•A high heating rate is critical to enable the removal of the surface oxide layers.•A high heating rate can help achieve oxide-free, well-sintered clean interfaces.•A slow heating rate leads to oxide-enveloped, poorly-sintered interfaces.•The influence of heating rate is attributed to the surface-cleaning effect of SPS.