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采用电沉积方法在Al基体上沉积Ni制备Ni-Al扩散偶,并研究扩散偶中Al3Ni和Al3Ni2的形成机理和生长动力学。在6061铝基体上采用直流电沉积方法制备20μm厚的Ni涂层。然后在Ar气气氛下,样品在450,500和550°C下热处理不同时间。采用扫描电子显微镜、能谱仪和X射线衍射仪对金属间化合物进行表征。结果表明,Ni-Al金属间化合物的形成可分为两个重要步骤。首先,金属间化合物在不同位置侧面生长,形成连续金属间化合物层;其次,连续金属间化合物层在垂直于界面方向继续生长。随着金属间化合物厚度的增长,Al3Ni和Al3Ni2等反应产物将与基体发生分离。Al是Al3Ni生长的主要扩散元素,而Ni是Al3Ni2生长的主要扩散元素。Al3Ni和Al3Ni2相的生长动力学遵循抛物线方程。
Electrodeposition was used to deposit Ni on Al matrix to fabricate Ni-Al diffusion couple. The formation mechanism and growth kinetics of Al3Ni and Al3Ni2 in diffusion couple were studied. A 20 μm thick Ni coating was prepared on a 6061 aluminum substrate by direct current deposition. The samples were then heat-treated at 450, 500 and 550 ° C for different times under an Ar atmosphere. The intermetallics were characterized by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometry. The results show that the formation of Ni-Al intermetallic compounds can be divided into two important steps. First, the intermetallic compound grows laterally at different positions to form a continuous intermetallic compound layer. Second, the continuous intermetallic compound layer continues to grow perpendicular to the interface. As the thickness of the intermetallic compound increases, reaction products such as Al3Ni and Al3Ni2 will separate from the matrix. Al is the main diffusion element of Al3Ni growth, and Ni is the main diffusion element of Al3Ni2 growth. The growth kinetics of Al3Ni and Al3Ni2 phases follow a parabolic equation.