A novel modulated diamond cutting (MDC) technique is proposed for the generation of complicated micro/nanofluidic channels. The MDC adopts a turning configuration through a four-axis ultra-precision diamond lathe, a motion modulation based milling operation is introduced by extending the virtual spindle technique. This unique principle makes the MDC more suitable to generate micro/nanofluidic channels through compromising certain inherent advantages of both diamond turning and milling. Moreover, taking advantage of axial servo motion modulation as well as tool mark modulation using the re-cutting e↵ect, complicated channels can be e↵ectively generated having spatially-varying shapes as well as hierarchical micro/nanostructures. Through both numerical simulation and experimental cutting, capability and outperformance of the MDC are demonstrated well. The result suggests that the MDC is capable to generate ultra-smooth channel surfaces with complicated shapes and superimposed surface nanostructures, exhibiting significant superiority for the generation of micro/nanofluidic channels with high flexibility, high e ciency, and high universality.

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A rapid method for grain growth of Ti6Al4V alloys induced by electropulsing treatment (EPT) was proposed in this study. The results show that the initial β grains could reach about 0.5 mm after EPT of 20 seconds, and the dramatic grain growth rate is attributed to the high atom diffusion and large driving force caused by the thermal and athermal effects of EPT. Grains stop coarsening as the average grain size reaches about 2.0 mm, even though the electropulsing duration is as long as 15 minutes. Driving force reduction and solute drag effect supposedly result in the grain growth stagnation. The corrosion and wear resistance of the large crystal alloy with martensites are improved compared with the as received alloy. Besides, machinability of Ti6Al4V alloys with equiaxial α/β phase and large crystal with martensites was investigated via ultraprecision diamond turning. Though the cutting force of the alloy with large crystals varies with the martnesitic orientations, the average cutting force and surface roughness were smaller that of the as received alloy.

The formation of serrated chips is an important feature during machining of difficult-to-cut materials, such as titanium alloy, nickel based alloy, and some steels. In this study, Ti6Al4V alloys with equiaxial and acicular martensitic microstructures were adopted to analyze the effects of material structures on the formation of serrated chips in straight line micro orthogonal machining. The martensitic alloy was obtained using highly efficient electropulsing treatment (EPT) followed by water quenching. The results showed that serrated chips could be formed on both Ti6Al4V alloys, however the chip features varied with material microstructures. The number of chip segments per unit length of the alloy with martensite was more than that of the equiaxial alloy due to poor ductility. Besides, the average cutting and thrust forces were about 8.41 and 4.53 N, respectively, for the equiaxed Ti6Al4V alloys, which were consistently lower than those with a martensitic structure. The high cutting force of martensitic alloy is because of the large yield stress required to overcome plastic deformation, and this force is also significantly affected by the orientations of the martensite. Power spectral density (PSD) analyses indicated that the characteristic frequency of cutting force variation of the equiaxed alloy ranged from 100 to 200 Hz, while it ranged from 200 to 400 Hz for workpieces with martensites, which was supposedly due to the formation of serrated chips during the machining process.

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