Science and Technology of Welding & Joining · 2017 · 19 citations · 36 references
EngineeringMaterials EngineeringMaterials ScienceCeramic MaterialsMechanical Behavior Of MaterialsMetallurgyAlloy SolidificationAlloysDiffusion BondingMetalsSolidification MicrostructureSolidification Of MetalsAlloy Solidification MicrostructureCracksFemtosecond Laser PulsesFiller MaterialsFiller MetalsIsothermal ProcessesMetal DissolutionMicrostructure
Slots with uneven width were cut by femtosecond laser in small plates of IN738LC superalloy to imitate service cracks. The ‘cracks’ were repaired by diffusion brazing using BNi-1a or a mixed filler alloy at 1100°C. The joint region was composed of isothermal solidification zone (ISZ), diffusion affected zone (DAZ) and precipitate zone (PZ). The compositions were different between the upper and lower ISZ due to the variation of gap width. The sample, repaired with two kinds of filler metals, had similar DAZ microstructure. PZ of mixed filler alloy bonded sample had a similar microstructure with that of BNi-1a, but less borides. The maximum gap sizes of complete isothermal solidification were almost the same for different filler alloys, followed a square root relationship with time. However, PZ of BNi-1a bonded was larger, resulting from a more base metal dissolution. The relationship between the PZ, ISZ and crack width is discussed.
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Dongyun Zhang, Wen Jie Niu, Xuanyang Cao et al. · Materials Science and Engineering A · 2015 · 722 citations