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采用强变形技术在金属间化合物Ni_3Al表层制备了纳米晶,并对其进行了低温退火处理。采用X射线衍射仪、透射电镜和显微硬度计对变形态和退火态Ni_3Al表层的相结构、晶粒形貌和显微硬度分布进行了研究。结果显示,350℃低温退火时,强变形时形成的fcc结构无序Ni固溶体重新有序化,部分转变为L12有序结构的Ni_3Al相。退火后,纳米晶Ni_3Al的晶粒尺寸没有明显长大,微观应变显著降低。退火后表层纳米晶的组织不均匀,细晶粒尺寸为10~20 nm,大晶粒尺寸仍小于100 nm。350℃退火后表层部分的显微硬度仍可达525 HV0.2,强变形的强化作用在低温退火后仍可保持。
Nanocrystals were prepared on the surface of Ni_3Al intermetallic compound by a strong deformation technique and annealed at low temperature. The phase structure, grain morphology and microhardness distribution of the deformed and annealed Ni_3Al surface were studied by X-ray diffraction, transmission electron microscopy and microhardness tester. The results show that the ordered Ni solid solution of fcc structure formed during strong deformation is reordered at 350 ℃ and partially transformed into Ni_3Al phase of L12 ordered structure. After annealing, the grain size of the nanocrystalline Ni_3Al did not significantly increase, and the microscopic strain was significantly reduced. After annealing, the microstructure of the surface nanocrystalline is inhomogeneous. The fine grain size is 10-20 nm and the large grain size is still less than 100 nm. The microhardness of the surface layer after annealing at 350 ℃ can still reach 525 HV0.2. The strengthening effect of the strong deformation can be maintained even after annealing at low temperature.