K417G　superalloy　is　widely　applied　in　gas　turbine　components　such　as　blades,　vanes,　and　nozzles.　In　this　work,　the　oxidation　behavior　and　mechanism　of　K417G　alloy　prepared　by　wide-gap　brazing　were　investigated　in　air　at　800,　900,　1000,　and　1100　°C.　Microstructures　of　the　bonded　joints　differ　in　the　wide-gap　braze　region　(WGBR)　and　base　metal　(BM).　The　surface　and　cross-sectional　morphology,　composition,　and　structure　of　specimens　were　analyzed　by　XRD,　SEM,　and　EDS　after　oxidation　tests.　The　experimental　data　demonstrate　that　the　WGBR　(wide-gap　brazed　region)　exhibits　markedly　superior　oxidation　resistance　compared　to　the　BM　(base　material)　under　elevated-temperature　conditions　exceeding　1000　°C.　This　performance　disparity　is　quantitatively　validated　by　oxidation　kinetics　analysis,　where　the　weight　gain　curve　of　the　WGBR　demonstrates　parabolic　oxidation　kinetics,　as　evidenced　by　its　significantly　lower　parabolic　rate　constant　relative　to　the　BM.　The　oxide　layers　of　the　BM　and　WGBR　are　similar　after　oxidation　at　high　temperatures　of　800–900　°C,　and　they　consist　of　an　outermost　layer　of　NiO,　a　middle　mixed　layer　of　Cr2O3,　and　an　innermost　layer　of　dendritic　Al2O3.　However,　when　the　temperature　is　between　1000　and　1100　°C,　the　NiO　on　the　surface　of　the　BM　spalls　of　due　to　thermal　expansion　coefficient　mismatch　in　coarse-grained　regions,　resulting　in　oxidation　mainly　divided　into　outer　layer　Cr2O3　and　inner　layer　Al2O3　and　TiO2.　Under　high-temperature　oxidation　conditions　(1000–1100　°C),　a　structural　transition　occurs　in　the　oxide　scale　of　the　BM,　with　the　underlying　mechanism　attributable　to　grain-coarsening-induced　oxide　scale　destabilization.　Specifically,　the　coarse-grained　structure　of　the　BM　(characteristic　grain　size　exceeding　50　μm)　is　exhibited.　Therefore,　the　WGBR　demonstrates　outstanding　oxidation　resistance,　as　evidenced　by　the　formation　of　a　continuous　Al2O3　scale　with　parabolic　rate　constants　of　about　1.38　×　10−3　mg2·cm−4·min−1　at　1100　°C.　©　2025　by　the　authors.