球磨纳米结构Fe40Al合金粉末及其冷喷涂沉积行为研究

目的研究冷喷涂用纳米结构Fe40Al合金粉末的球磨制备工艺及其在不同基体表面的冷喷涂沉积行为。方法以Fe粉、Al粉为原料,按照Fe-40Al进行配比混合,采用行星式球磨机制备纳米结构Fe40Al合金粉末,在不同硬度基体表面(不锈钢、低碳钢、纯铜及锡)冷喷涂沉积单个Fe40Al合金粉末颗粒。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM),分析球磨过程中Fe40Al合金粉末的组织结构演变规律、粉末颗粒在不同基体表面的碰撞变形行为及沉积特性。结果球磨过程中,随着球磨时间的延长,Al扩散进入Fe晶格形成纳米结构Fe(Al)固溶体,球磨36 h后,Fe40Al合金粉末的晶粒尺寸约为35 nm,平均颗粒尺寸约为20μm,内部为精细层状结构。纳米结构Fe40Al合金粉末在硬度较高的不锈钢和低碳钢基体上沉积时,粉末颗粒发生强塑性变形而基体变形量较小,颗粒和基体间的结合较弱,沉积效果较差;当在硬度较低、塑性较好的Cu基体上沉积时,基体与粉末颗粒同时发生塑性变形,颗粒和基体间的结合较强,沉积效果最好;在硬度最低的Sn基体上沉积时,基体发生强烈的塑性变形且出现部分熔化,但颗粒几乎没有变形,且颗粒与基体间的结合很弱,沉积效果最差。结论采用球磨工艺可制备出适合冷喷涂用的纳米结构Fe40Al合金粉末,随着球磨时间的延长,粉末晶粒尺寸减小,硬度增加。基体种类对纳米结构Fe40Al合金粉末的冷喷涂沉积行为影响显著,基体硬度过高或过低均不利于粉末颗粒沉积,基体与粉末颗粒同时发生塑性变形有利于增强颗粒与基体间的界面结合,从而改善沉积效果。

Ball-milled Nanostructured Fe40Al Alloy Powder and Its Deposition Behavior in Cold Spray Process

The work aims to study ball-milling preparation technology of nanostructured Fe40Al alloy powder for cold spraying use and its cold spraying deposition behavior on different substrates. Fe and Al powder was mixed according to Fe-40Al (at.%) and milled in a planetary ball mill to prepare nanostructured Fe40Al alloy powder. Single Fe40Al alloy powder particle was deposited on the surfaces of four substrates of different harness (stainless steel, low carbon steel, pure copper and Tin) by cold spraying. Structural evolution of the Fe40Al alloy powder during ball milling, and its collision deformation beha-vior and deposition characters on different substrates were analyzed with X-ray diffractometer (XRD) and scanning electron mi-croscope (SEM). Al atom diffused into Fe lattice and finally formed nanostructured Fe(Al) solid solution as the ball milling time extended. After 36 hours of milling, grain size and average particle size of the Fe40Al alloy powder were approximately 35 nm and 20 μm, respectively, and the powder exhibited refined platelike microstructure. When depositing on stainless steel and low carbon steel substrates of relatively high hardness, nanostructured the Fe40Al alloy powder was subject to intensive plastic de-formation while the substrate was subject to little deformation. The deposition effect was not good due to relatively poor bond-ing condition between the particle and substrate. When depositing on Cu substrate of relatively lower microhardness and good plasticity, both the Fe40Al alloy powder and substrate were subject to intensive plastic deformation and deposition effect was the best due to favorable bonding condition between the particle and substrate. When depositing on Sn substrate of the lowest microhardness, the substrate was subject to intensive plastic deformation and even partial melting in local impacting area, depo-sition effect was the poorest due to weak bond condition between the intact particle and substrate. Nanostructured Fe40Al alloy powder as feedstock of cold spraying process can be fabricated by ball milled process. The grain size of Fe40Al alloy powder decreases while microhardness increases as the ball milling extends. Substrate type has significant effect on the deposition beha-vior of Fe40Al alloy powder during cold spraying. The Fe40Al alloy powder exhibits relatively poor deposition effect when substrate microhardness is too high or too low. The optimal deposition effect can be obtained since intensive plastic deformation of both the substrate and powder particle contributes to interface bonding between the particle and substrate.