纳米晶Ni_3Al低温退火时的组织转变  

Microstructure evolution of Ni_3Al nanocrystal during low temperature annealing

作　　者：任江伟[1] 李东[1] 

机构地区：[1]上海工程技术大学材料工程学院,上海201620

出　　处：《金属热处理》2016年第6期63-67,共5页Heat Treatment of Metals

基　　金：上海工程技术大学高水平培养项目(2012gp25)

摘　　要：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。Nanocrystal was prepared on the surface of Ni3AI intermetallic compound by severe plastic deformation technology and then annealed at low temperature. Phase structure, grain morphology, microhardness distribution of deformed and annealed samples were studied by X-ray diffractometer, transmission electron microscope and microhardness tester. The results show that the ordering occurs when the deformed sample is annealed at 350℃, the Ni solid solution with face-centered cubic structure formed during the severe plastic deformation transforms to the ordered Ni3A1 with L12 structure partly. Grains of Ni3A1 nanocrystals are not obvious coarsen and microstrain releases remarkable after annealing, and the microstructure of nanocrystal on surface layer is inhomogeneous. The grain size is about 10-20 nm in fine grain zone and that in relative coarse zone is less than 100 nm. The microhardness of the surface layer can still reach 525 HV0, 2, which means the strengthening effect introduced by severe plastic deformation can be kept after annealed at 350 ℃.

关 键 词：NI3AL金属间化合物 纳米晶 低温退火 组织 

分 类 号：TG166.7[金属学及工艺—热处理]