The connection cross section of a Ti-based bulk metallic glass welded with friction stir spot welding method, was investigated using Vickers micro-hardness and SEM. Regarding the results, four zones were detected at the connection site. The crystallization kinetics of the four zones identified at the joining area, was studied using the DSC at heating rates of 10–50 K min−1. Apparent activation energy (Ec), frequency factor (A) at characteristic temperatures (Tg, Tx1, Tp1) and local activation energy (Ec(α)) variations of different zones during the first crystallization transformation were calculated by isokinetics and isoconversional models. The crystallization conversion function for each zone was determined using the Sestak-Berggren equation. Sub-tool tip stir zone (TSZ) showed the highest thermal stability. The thermo-mechanically affected zone (TMAZ) with the highest onset crystallization temperature (Tx1) has a higher thermal stability in comparison to sub-tool shoulder stir zone (SSZ) with the lowest thermal stability and base metal (BM).The connection cross section of a Ti-based bulk metallic glass welded with friction stir spot welding method, was investigated using Vickers micro-hardness and SEM. Regarding the results, four zones were detected at the connection site. The crystallization kinetics of the four zones identified at the joining area, was studied using the DSC at heating rates of 10–50 K min−1. Apparent activation energy (Ec), frequency factor (A) at characteristic temperatures (Tg, Tx1, Tp1) and local activation energy (Ec(α)) variations of different zones during the first crystallization transformation were calculated by isokinetics and isoconversional models. The crystallization conversion function for each zone was determined using the Sestak-Berggren equation. Sub-tool tip stir zone (TSZ) showed the highest thermal stability. The thermo-mechanically affected zone (TMAZ) with the highest onset crystallization temperature (Tx1) has a higher thermal stability in comparison to sub-tool shoulder stir zone (SSZ) with the lowest thermal stability and base metal (BM).

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