Diamond turning is an effective technology for processing metal mirrors used in photoelectric communications, radar, and other fields. In diamond turning, the precipitated phase is an essential factor that influences the surface quality of the metal mirrors. However, in previous studies, the precipitation phase has typically been handled as a random variable in a surface morphology model to evaluate its influence on the surface roughness, instead of determining the formation mechanism and proposing suppression solutions. In this study, a new phenomenon is observed in the diamond turning of metal mirrors, that is, the micro diamond tool can reduce the protrusion of the precipitated phase under a small feed rate and improve the surface quality. Investigating the turning process using diamond tools with varying tool nose radii at small feed rates (<1 μm/r), the underlying transformation mechanism of the precipitation phase is determined with the advanced material characterization technologies. The growth of the precipitated phase with an increase in the tool nose radius is explained using the energy gradient theory. The results showed that the increased material strain on the machined surface decreased the activation energy of solute diffusion in the material, causing solute accumulation and precipitate phase growth. With a further increase of tool nose radius to around 1000 μm, the β'' phase breaks and rotates. The representative volume element method shows that when undergoing severe plastic deformation, dislocations and grain boundaries quickly aggregate and slide on the precipitated phase, which will lead to the fracture and rotation of β'' phase. These findings provide a theoretical basis for the development of highly smooth mirrors.

中文翻译：

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深入研究析出相对铝合金金刚石车削表面质量的影响


金刚石车削是加工光电通信、雷达等领域金属镜面的有效技术。在金刚石车削中，析出相是影响金属镜表面质量的重要因素。然而，在以前的研究中，沉淀相通常被视为表面形貌模型中的随机变量，以评估其对表面粗糙度的影响，而不是确定形成机制并提出抑制解决方案。本研究在金属镜面金刚石车削中观察到一个新现象，即微型金刚石刀具可以在小进给量下减少析出相的突出，提高表面质量。研究使用具有不同刀尖半径的金刚石刀具在小进给率 (<1 μm/r) 下的车削过程，通过先进的材料表征技术确定了沉淀相的基本转变机制。使用能量梯度理论解释了随着刀尖半径的增加析出相的生长。结果表明，加工表面材料应变的增加降低了溶质在材料中扩散的活化能，导致溶质积累和沉淀相生长。随着刀尖半径进一步增加到 1000 μm 左右，β'' 相破裂并旋转。代表性体积元法表明，当发生剧烈的塑性变形时，位错和晶界在析出相上快速聚集和滑动，导致β''相的断裂和旋转。这些发现为高光滑镜子的开发提供了理论基础。