应材料科学与工程学院黄陆军教授、张宇特任副研究员的邀请，俄罗斯圣彼得堡国立海洋技术大学Sergey Zherebtsov教授于2025年08月06日举行学术讲座，题目为“Effect of laser shock peening on structure and properties of metallic materials” and “Effect of high pressure torsion on structure and properties of metallic materials-matrix composites”，欢迎感兴趣的师生参加。

讲座时间：2025年08月06日，9:30 (北京时间)

讲座地点：中文字幕av 708会议室

摘要1：Laser shock peening (LSP) is an innovative technique which can be used to enhance the fatiguestrength of structural materials via the generation of significant residual stress. The present work wasundertaken to evaluate the degree of plastic strain introduced during LSP and thus improve the fundamental understanding of the LSP process. To this end, electron backscatter diffraction (EBSD) and nano-hardness measurements were performed to examine the microstructural response of Ti-6Al-4V alloy ARMCO iron to laser shock peening. Only minor changes in both the shape of

grains/particles, dislocation density and hardness were found in Ti-6Al-4V while noticeable changes in microstructure and properties were noticed in the case of ARMCO iron. It was concluded that the laser-shock-peened material only experienced a relatively small plastic strain which also depended on the yield strength of the material. Such a relatively minor response on LSP was attributed to a rather high rate of strain hardening of materials during LSP.

摘要2：Severe plastic deformation (SPD) is a well-known method for improving the mechanical properties of metallic materials via significant refining the microstructure. Grain size reduction results in strengthening of titanium and titanium alloys, making them strong enough for the production of, for example, medical implants. Another promising approach to increase the strength of titanium alloys without losing biocompatibility and corrosion properties may be associated with the introduction of ceramic reinforcing elements, such as TiB, into the titanium-based matrix. SPD of such metal-matrix composites (MMCs) thus causes the simultaneous action of several strengthening mechanisms. TiNbZr alloy reinforced with (Ti,Nb)B was obtained by vacuum arc melting and then subjected to severe deformation using high-pressure torsion (SPD) at 300 °C. Three alloy compositions with different amounts of (Ti,Nb)B (1.0 vol.%, 6.8 vol.% and 13.2 vol.%) were studied. The microstructures of the composites after HPT showed an increase in dislocation density, a significant decrease in grain size (to 300-500 nm) in the metal matrix, and a refinement of borides to 20-40 μm. Then, the microstructure evolution and mechanical behavior of the metal matrix composites after HPT were investigated during deformation in the temperature range of 300-600°C. The composite with 6.8 vol.% borides showed much higher ductility (compared to the other two conditions), achieving more than 100% elongation at 400, 500, and 600°C. The highest elongation was observed at 500°C and a strain rate of 7.5×10-4s-1, where the strain sensitivity was found to be m=0.33. Microstructure analysis suggests that the very limited plasticity of MMC may be associated with the destruction of (Ti,Nb)B filamentary crystals and the further propagation of crack nuclei into the nanostructured matrix.

个人简介：Sergey Zherebtsov achieved his Ph.D. degree from Institute for Metals Superplasticity Problems, Ufa, Russia in 2002 and a Dr. habil., Phys. Metallurgy, Ural Federal University, Ekaterinburg, Russia in 2013. From 2002 to 2006, he worked in Ufa State Aviation Technical University as a lecturer (Ufa, Russia), Ibaraki University as a researcher (Hitachi, Japan), Institute for Metals Superplasticity Problems as a Research Associate (Ufa, Russia). In 2007, he joined in Belgorod State University and became a full-time professor. In 2024, he joined in Petersburg State Marine Technical University as a full-time professor. His research interests are about formation of ultrafine-grain microstructure in titanium and titanium alloys via warm large plastic working. Development of high-entropy alloys with specified structure and properties. Extensive TEM/SEM/EBSD studies of structural changes during plastic deformation. Effect of hot/warm/cold working on microstructure, including evolution of interphase and grain boundaries. Evaluation of mechanical properties of metals and alloys.