(1. 上海工程技术大学 材料工程学院，上海 201620；
2. 上海交通大学 材料科学与工程学院，上海 200240)
摘 要: 采用表面机械研磨技术在定向凝固态和铸造态Ni3Al表面制备纳米结构表层，采用扫描电镜、XRD和TEM等对纳米结构表层的组织特征进行研究，探讨定向凝固和铸造两种制备状态对Ni3Al表面纳米结构组织特征的影响。结果表明：经过相同工艺表面机械研磨处理后，两种制备状态的Ni3Al发生了无序化转变和晶粒细化，但两者的表层组织特征间存在显著差异；铸造态Ni3Al试样中Ni(Al)固溶体的含量达65%，远高于定向凝固态Ni3Al试样中的7%；铸造态试样表层的晶粒尺寸约为56 nm，远大于定向凝固态试样的22 nm；两种Ni3Al试样制备态时，化学成分和显微硬度的差异可能是造成这种差异的原因。
关键字: 金属间化合物；Ni3Al；表面机械研磨处理；塑性变形；微观组织
surface nanocrystallized Ni3Al
（1. College of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620, China;
2. School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China）
Abstract:The influence of two initial states, such as directional solidified and as-cast, on the microstructure of surface of nanocrystallized Ni3Al was investigated. The nanostructure layers were prepared on the surface of Ni3Al with different initial states by means of surface mechanical attrition treatment (SMAT). The characteristics of surface nanostructure layer were examined by scanning electronic microscopy (SEM), X-ray diffractometry (XRD) and transmission electronic microscopy (TEM). The results indicate that the transformations, such as disordering and grain refining, occur in all samples with different initial states after surface mechanical attrition treatment. However, obvious difference exists in the relative content of solid solution and the grain size of Ni3Al nanograins between the samples with two initial states. The Ni(Al) solid solution of as-cast Ni3Al surface reaches 65% and the grain size is about 56nm after surface mechanical attrition treatment. The directional solidified Ni3Al has less Ni(Al) solid solution (7%) and smaller grains (abut 22nm). This phenomenon may be attributed to the difference of the two initial states in chemical composition and microhardness.
Key words: intermetallic; Ni3Al; surface mechanical attrition treatment; plastic deformation; microstructure
