The objective of this study is to investigate the influence of various tissue loads on the working characteristic of the ultrasonic scalpel, including working frequency, input admittance and reflection factor. Ex vivo animal experiments are carried out and relevant discussions of experimental results are provided. Admittance measurement results show that different tissue loads have different effects on a scalpel's working ability. Soft tissue makes the working frequency decrease and bone tissue makes it increase. Radius of admittance circles and reflection factor are also different. Equivalent circuit model is found and with a least-square parameter identification method, input admittance of ultrasonic scalpel with different tissue loads is solved. Results show that admittance circle radius is determined by the value of R1. Changes in L1 and C1 contribute to the shift of working frequency. This study will help decrease the sensitivity of ultrasonic scalpel to loads and greatly increase surgery efficiency.

Ti6Al4V alloy has been considered as a key component used in ultrasonic scalpels. In this series of papers, the fabrication, structure, and mechanical and ultrasonic properties of medical Ti6Al4V alloys suitable for ultrasonic scalpel are studied systemically. These alloys with low elastic modulus and present a typical bimodal microstructure with relatively high β phase content (~40%) and lamellar α thickness of ≤ 0.9 µm. In the first paper, the relationship between the microstructure and mechanical properties of hot-rolled Ti6Al4V alloys treated by heating treatment is discussed. In the second paper, the dependence of the ultrasonic properties on the microstructure of the heat-treated Ti6Al4V alloys is reported. With increasing solid solution temperature, the content and size of the primary α phase decrease. In contrast, the content and size of the lamellar α phase increase. Additionally, the β phase content first increases and then decreases. The microstructure of Ti6Al4V alloys could be slightly changed by aging treatment. When the solid solution treatment temperature increases to 980 °C from 960 °C, the average size of the lamellar α phase in the alloys increases by 1.1 µm. This results in a decrease in the average yield strength (93 MPa). The elastic modulus of alloys is mainly controlled by the β phase content. The microstructure of alloys by solution-treatment at 960 °C shows the highest β phase content and lowest average elastic modulus of 99.69 GPa, resulting in the minimum resonant frequency (55.06 kHz) and the highest average amplitude (21.48 µm) of the alloys at the length of 41.25 mm.

The ultrasonic surgical aspirator employs a vibrating metal tip to fragment tissue and then aspirates the debris through the hollow center of the tip. The mechanism of interaction has been stated to be poorly understood, most likely related to cavitation, possibly in concert with other mechanical actions. In Part I (of two parts), the role of stroke, suction, frequency, tissue type and tip area are examined with regard to tissue fragmentation rate. A tissue quantifier which can be used to relate the performance of the ultrasonic aspirator and a selected tissue is described. Suction is shown to make a significant contribution to the interaction. Thermal and tip load experiments are used to estimate the acoustic pressures and powers at the tip. In Part II, photographic and acoustic data from experiments in water and on a range of fresh pig tissues are used to further investigate the fragmentation effect.

In this study, the ultrasonic resonance parameters of Ti6Al4V alloys under different heat treatments are measured by an impedance analyzer. The amplitude of the specimens is measured experimentally by means of optical microscope and image analysis software. These results show that the ultrasonic properties of Ti6Al4V alloys are closely related to β phase content and elastic modulus of the alloys. The highest volume fraction of the β phase appears in the specimen treated by solid solution treatment at 960 °C is 40.2%. These alloys present the lowest average elastic modulus (~99.69 GPa) and the minimum resonant frequency (55.06 kHz) and the highest average amplitude (21.48 µm) when the testing sample length is 41.25 mm. These findings can be used to guide the design of medical Ti6Al4V alloys for ultrasonic scalpels.

The influence of Fe- and Cu-content on the microstructure and mechanical properties of TC10 alloy bars was investigated by means of scanning electron microscopy, EDS analysis of transmission electron microscopy, and mechanical testing machine. The results indicate that for the as rolled and annealed TC10 Ti-alloys, with the increasing Fe- and Cu-content, their yield strength and tensile strength increase, while the changes in elongation and cross-sectional shrinkage at break are not significant. For the solid solution aged TC10 alloy, Ti is evenly distributed in both βt and αp phases, Al is less distributed at grain boundaries, while V, Fe, and Cu elements are more abundant at the grain boundaries in βt phase. For TC10 alloys with the same Fe- and Cu-content, with the increasing solid solution temperature, their yield strength and tensile strength increase, while the elongation and cross-sectional shrinkage decrease. For TC10 alloys subjected to solid solution treatment at the same temperature, with the increase of Fe and Cu content, their yield strength and tensile strength increase, while the elongation and cross-sectional shrinkage at break decrease. The higher the solid solution temperature, the more significant the influence of alloying elements Fe and Cu on the strength and plasticity of the alloy. Being subjected to solid solution treatment at 900 oC, the alloy with 0.65% Fe and 0.65% Cu can achieve superior comprehensive mechanical properties, with yield strength, tensile strength, elongation, and cross-sectional shrinkage at break of 1392 ± 3 MPa, 1435.5 ± 0.5 MPa, (8 ± 1)% and (21.5 ± 1.5)%, respectively.

Titanium (Ti) and its alloys are used in various applications, including aircraft frames, ship parts, heat exchangers, and evaporator tubes, because of their extraordinary properties, such as high specific strength, excellent corrosion resistance at high temperatures, good castability, and weldability. Plastic deformation plays a crucial role in securing the appropriate microstructure and strength of Ti and alloys in these applications. The rolling process, one of the most useful methods for plastic deformation, causes efficient deformation inside the materials, resulting in grain refinement, dislocation slip, and twinning. Recent studies on the rolling behaviors of Ti and its alloys have explored their crystallographic and mechanical properties. These investigations primarily analyzed the microstructural changes and their influence on the mechanical properties under different temperatures and rolling methods. This study elucidates a complex relationship between the processing conditions and the resulting properties. Therefore, this paper presents a comprehensive review of the state-of-the-art Ti rolling. Various key aspects for verifying the microstructure of Ti and its alloys are discussed, including electron backscatter diffraction analysis, Schmidt factor, and misorientation distribution.

Herein, the effect of heat treatments (solution, solution+single aging and solution+double aging) on the microstructure and mechanical properties of a novel Ti-based alloy Ti-6Al-2Mo-2V-3Nb-2Fe-1Zr was investigated through microstructure characterization and tensile testing. The microstructure observations indicate that the alloy prior to heat treatment possesses a bimodal microstructure consisted of primary αp phase, secondary αs phase, and β phase, and the volume fraction of the primary αp phase and secondary αs phase is 22% and 21%, respectively. After solution treated in the dual phase zone, a portion of the original αp and αs phases was replaced by β phase and the alloy microstructure is comprised of metastable β phase, equiaxed primary αp phase, and coarse lamellar secondary αs phase. After single aging, a large number of evenly distributed needle-like nano secondary αs phases are precipitated within the β phase; After double aging, the volume fraction of α phase increases significantly, while the grain size of primary αp phase and secondary αs phase increases with the increasing aging time. Quasi-static tensile test results reveal that alloys subjected to solution treatment in the dual phase zone exhibit significant enhancements in elongation compared to the as hot-rolled ones, but yielding at lower stress levels. Single aging results in significant increase of strength, thereby presenting an improved strength-ductility balance of the alloy. In comparison with the hot rolling process, the double aging process is unfavored to the ductility, moreover, with the increasing aging time, the strength decreases and elongation increases gradually. Finally, the variation in the work hardening rate of the alloy subjected to different heat treatments may be explained by work hardening rate-strain curves. Based on the experimental data, the modified Hall-Petch constitutive model is fitted, whilst the results predicted by this constitutive model have high coincidence with the experimental data.

研究了固溶、固溶+单级时效和固溶+双级时效三种热处理制度对Ti-6Al-2Mo-2V-3Nb-2Fe-1Zr合金的微观组织和力学性能的影响。结果表明，这种合金热处理前的组织为双态组织，由初生α_p相、次生α_s相和β相组成，其中初生α_p相的体积分数为22%，次生α_s相的体积分数为21%；在双相区固溶后，合金原来的热轧态α_p和α_s相部分转变为β相，其组织由亚稳β相、等轴状初生α_p相和粗大片状的次生α_s相组成；单级时效后，β相中析出了大量均匀分布的纳米细针状次生α_s相；双级时效后α相的体积分数显著提高，随着时效时间的增加初生α相和次生α相的晶粒尺寸逐渐增大。准静态拉伸实验结果表明，与热轧态试样相比双相区固溶态试样的延伸率显著提高，但是屈服强度明显降低；单级时效后试样的强度显著提高，强度-塑性平衡更佳；与热轧态试样相比，双级时效后试样的延伸率有所降低，随着时效时间的增加合金的强度降低而延伸率提高。用加工硬化率曲线解释了不同热处理的钛合金应变硬化率的变化趋势，并基于实验结果拟合了修正的Hall-Petch模型，与实验结果吻合较好。