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采用透射电镜,X射线衍射和硬度测量等方法研究了Ni-Fe-Nb-Al合金调幅结构的形成和生长,认为是典型的调幅结构。合金中Al原子的加入,加速了合金调幅结构的生长。在早期时效阶段,γ′[Ni_3(Al,Nb)]预沉淀相沿〈100〉三个方向周期的排列。在[001]和[011]晶带衍射条件下,显微象呈平行条纹,其条纹间隔为100A。随着时效的延长,显微象呈现出花呢结构。更进一步时效,平行条纹间距增大一倍为200A。合金在550,700和800℃三种温度下,时效10h后,γ′沉淀相在调幅结构的条纹上析出,颗粒沿[100]和[010]两方向规则排列。在各种时效制度下,合金的X射线衍射圈(220)主峰旁均出现一侧边峰。根据调幅结构的生长过程与合金硬度的变化规律,探讨了Ni-Fe-Nb-Al合金在时效过程中硬化的本质.解释了Ni-Fe-Nb-Al合金比Ni-Fe-Nb合金硬度高的原因。
The formation and growth of the amplitude modulation structure of Ni-Fe-Nb-Al alloy were investigated by TEM, X-ray diffraction and hardness measurement. It is considered as a typical amplitude modulation structure. The addition of Al atoms in the alloy accelerates the growth of the AM structure. In the early stage of aging, the arrangement of γ ’[Ni_3 (Al, Nb)] pre-precipitation phases along <100> three-direction cycles. Under the [001] and [011] band diffraction conditions, the microscopic images show parallel stripes with a stripe spacing of 100A. With the prolongation of time, the microscopic image shows a tweed structure. Further aging, doubling the parallel stripes spacing is 200A. After aging at 550, 700 and 800 ℃ for 10h, the precipitates of γ ’precipitate on the stripes of the amplitude modulation structure, and the particles are regularly arranged in [100] and [010] directions. Under various aging regimes, one side peak appears beside the main peak of X-ray diffraction (220) alloy. The essence of hardening of Ni-Fe-Nb-Al alloy during aging was discussed based on the growth of AM structure and the variation of alloy hardness. It is explained that the hardness of Ni-Fe-Nb-Al alloy is higher than that of Ni-Fe-Nb alloy s reason.