Ni_(3)Al合金蜂窝的制备及微观组织演变规律

Study on the Preparation and Microstructure Evolution of Ni_(3)Al Alloys Honeycomb

目的研究Ni-Al扩散偶在热扩散过程中的微观组织演变规律,提出Ni_(3)Al合金蜂窝形成的模型。方法采用电镀技术在易加工的Al蜂窝表面电镀一定厚度的Ni,研究热扩散温度和时间对Ni-Al扩散偶组织结构的影响。采用X射线衍射仪对Ni-Al扩散偶进行物相分析;通过扫描电镜技术对Ni-Al扩散偶截面进行形貌及能谱分析,推测微观组织演变规律。结果热扩散温度为500℃时,随着热扩散时间的延长,Ni-Al界面处首先出现NiAl_(3),然后消失,最终形成以Ni_(2)Al_(3)为扩散层主体、NiAl和Ni_(3)Al为过渡层的多层实心结构;热扩散温度为700、1100℃时,Ni-Al扩散偶会分别形成以Ni_(2)Al_(3)、NiAl为内芯,纯Ni为外壳,并以NiAl、Ni_(3)Al薄层过渡的多层中空结构;热扩散温度为1300℃时,随着扩散时间的延长,Al相夹心层从Al、NiAl_(3)、Ni_(2)Al_(3)三相混合结构依次转化为成分均一的单相Ni_(2)Al_(3)和NiAl结构,扩散时间继续延长,Ni层随之耗尽,Ni-Al扩散偶最终形成以γ′-Ni_(3)Al为强化相的Ni-Al合金。结论Ni-Al固相扩散反应过程中,随热处理温度的提升,Al原子发生了明显的外扩散。Ni-Al液固扩散反应过程中,随热处理时间的延长,Ni原子发生了明显的内扩散。在1300℃热扩散1 h的条件下,能成功制备Ni_(3)Al基合金蜂窝壁。

The work aims to study the microstructure evolution of Ni-Al diffusion couple in the thermal diffusion process so as to put forward a formation model of Ni_(3)Al alloy honeycomb.Ni was electroplated on the surface of easily processed Al honeycomb so as to study the influence of thermal diffusion temperature and time on the Ni-Al honeycomb microstructure.The phase composition of Ni-Al diffusion couple was analyzed by X-ray diffractometer.The section of Ni-Al diffusion couple was analyzed by scanning electron microscope and energy dispersive spectroscopy technique,and the microstructure evolution of Ni-Al diffusion couple was speculated.Through the analysis of the microscopic morphology,energy dispersive spectrum elements and X-ray diffraction of Ni-Al diffusion couple after thermal diffusion,it was found that NiAl3 appeared in the Ni-Al interface,and then disappeared,therefore a multilayer solid structure with Ni2Al3 as the main diffusion layer and NiAl and Ni_(3)Al as the transition layer formed,with the extension of thermal diffusion time,at a thermal diffusion temperature of 500.At a thermal℃diffusion temperature of 700℃and 1100℃,Ni-Al diffusion couples formed a multilayer hollow structure with Ni2Al3 and NiAl as the main diffusion layer,thin NiAl and Ni_(3)Al as the transition layer and pure Ni as the shell.At a thermal diffusion temperature of 1300℃,with the extension of diffusion time,the Al-phase intermediate layer transformed a three-phase mixed structure of Al,NiAl3 and Ni2Al3 into single-phase Ni2Al3 and NiAl structure with uniform composition in turn.With the diffusion time continuing prolonging,the Ni layer was exhausted.Finally,The Ni-Al diffusion couple formed a Ni-Al alloy withγ′-Ni_(3)Al as the strengthening phase.In conclusion,Al atoms significantly diffuse outward in the Ni-Al solid phase diffusion process with the temperature increasing.Ni atoms significantly diffused inward in the Ni-Al solid-liquid diffusion process with the thermal diffusion time extension.After annealing at 1300℃for 1h,the Ni_(3)Al-based alloy honeycomb is successfully prepared.