An ultrasonic vibration–assisted micro-milling with horizontal vibration of workpiece is investigated in this article. A vibration platform with maximum amplitude of 15 μm based on universal ball support structure is designed and built by our group. Titanium alloy TC4 and aluminum alloy 6061T6 were chosen as workpiece material. Series of slot-milling experiments were conducted with and without vibration at different amplitudes and feed rates to explore the effects of vibration on the micro-milling. Experiment results showed that ultrasonic vibration can effectively reduce milling force by 12% and 17%, respectively, for aluminum alloy 6061T6 and titanium alloy TC4 compared with that of conventional milling and hence leading to a better machining accuracy and longer tool life. Furthermore, the effect of ultrasonic vibration on titanium alloy is much more obvious. The topographies of machined surfaces also showed that ultrasonic vibration can reduce surface defects and machining marks and thus improve the surface quality for both 6061T6 and TC4. Besides these, it is worth to be noted that ultrasonic vibration leads the size effect point appear at much lower feed rate than conventional milling, which means vibration brings a change to machining mechanism and delays the appearance of micro-milling.

This study carried out a novel duplex surface treatment on aluminum alloy base to explore the potential improvement of wear and corrosion resistance. Regular arrayed dimple surface texture (DST) and groove surface texture (GST) were fabricated by using laser processing on 6065 aluminum alloy matrix (6065Al). Electrochemical deposition of Ni and Graphene/Ni coatings on textured surface was then performed in electrolytes with concentrations of 0, 0.5, 1 and 1.5 mg graphene. Surface morphology such as diameter of dimple and width of groove measured by C-PSCN stereo microscope presents addition of graphene helps to refine and homogenize the coating. Corrosion resistant properties of the duplex surface treatment were examined by electrochemical corrosion tests and wear resistant properties were tested by UMT-Tribo Lab friction and wear tester in a dry sliding condition at room temperature. Electrochemical corrosion tests results show that the corrosion resistance of samples is related to the specific surface texture and the dimple texture can improve the electrical corrosion parameters, such as the electrode potential, greatly. Friction and wear tests show that the textured Gr/Ni electroplating coating with the 1.5 mg graphene content has best wear properties under vertical friction and each index, such as the coefficient of friction and wear trace width, are superior to other conditions of samples.

As an effective method for the fabrication of miniature metallic parts, the development of micro-forming process (MFP) is still restricted by the existence of size effect. To improve the micro-forming performance of metal material, ultrasonic vibration assisted MFP had been studied extensively for its superiorities in improving materials flow stress and reducing interfacial friction. However, from the literature available, the high frequency vibration was usually found to be superimposed on the forming tool while seldom on the workpiece. Our group developed a special porous sonotrode platform which can realize tool vibration and workpiece ultrasonic vibration independently. In this work, ultrasonic micro-extrusion experiments for copper T2 material under tool vibration and the workpiece vibration condition, respectively, were conducted for comparing the micro-forming characteristic of different vibration modes. The micro-extrusion experiment results of copper T2 show that the lower extrusion flow stress, the higher micro-extrusion formability and surface micro-hardness, and more obvious grain refinement phenomenon can be obtained under the workpiece vibration condition compared with that of tool vibration. These findings may enhance our understanding on different ultrasonic forming mechanisms and energy transmission efficiency under two different vibration modes.

In this paper, plain aluminum was chosen as matrix alloy and graphene reinforced aluminum alloy composites was successfully prepared via powder metallurgy approach. Micro-milling experiments were conducted to explore the effect of varying graphene nanoflakes (GNFs) content (0.5%, 1.0%, and 1.5% by weight) on the machinability of composites and their machining results were compared with that of plain aluminum. Chip morphology, milling force, and machined surface morphology were used as the machinability measures. Experiment results showed that when the content of GNFs is less than 1.5%, the grain refinement of GNFs plays a major role. The hardness and density of the composites are increased. When the content of GNFs is more than 1.5%, the agglomeration phenomenon is obvious, which reduces the hardness and density of the composites. Micro-milling results show that the milling force is the highest when the GNFs content is 1%, and curling degree of chips increased as FPT increase for a certain content of graphene of composites. Furthermore, when the content of GNFs in composites is more than 1%, the surface roughness of milling grooves is greatly improved, which may be related to the lubrication of graphene and the formation of continuous chips.

Thermoplastic microforming not only breaks through the bottleneck in the manufacture of metallic glasses, but also offers alluring prospects in microengineering applications. The microformability of metallic glasses decreases with a reduction in the mold size owing to the interfacial size effect, which seriously hinders their large-scale applications. Here, ultrasonic vibration was introduced as an effective method to improve the microformability of metallic glasses, owing to its capabilities of improving the material flow and reducing the interfacial friction. The results reveal that the microformability of supercooled Zr₃₅Ti₃₀Cu_8.25Be_26.75 metallic glasses is conspicuously enhanced by comparison with those under quasi-static loading. The more intriguing finding is that the microformability of the Zr-based metallic glasses can be further improved by tuning the amplitude of the ultrasonic vibration. The physical origin of the above scenario is understood, in depth, on the basis of ultrasonic vibration-assisted material flow, as demonstrated by the finite element method.