报告题目：N for strength and elongation in some high Ni alloys and HEA alloys

报告内容简介：

The materials with high strength and high elongation are desirable. Introduction of deformation twins can increase both strength and ductility of some metallic materials. The phenomenon is called twin induced plasticity behaviour or TWIP behaviour. Formation of deformation twin are strongly dependent on the stacking fault energy of the material. In this presentation, the TWIP behaviours in some Ni based alloys and high entropy alloys, HEAs are discussed. It was found that the formation of deformation twins is not determined solely by stacking fault energy. It is the critical strain and deformation hardening rate that influence the occurrence of deformation twinning and twinning rate. Nitrogen, N is usually added to increase both strength and corrosion resistance of the metallic materials such as steels. Addition of N is known to increase the stacking fault energy of the alloy. However, addition of N in some steels and HEA alloys increases not only the strength but also the elongation at ambient temperature by formation of deformation twins. At cryogenic temperature, on the other hand, the deformation twinning rate or density of deformation twins in the N alloyed material is less than that without N addition. The mechanism is discussed with an ab initio calculation.

报告人姓名：Guocai Chai

报告人简介：Professor Guocai Chai is currently an adjunct professor in Engineering Materials at Linköping University, and the group expert at Alleima group, Sweden. His research areas are alloy design and material development, correlation between microstructure and properties, and material mechanics. He is the board member of the Swedish Royal Mechanics Society, the board member of Swedish Society for Materials and Technology, the management committee member of the European creep collaboration committee, ECCC. He was an EU expert for the Horizon 2020/RFCS program and the invited international independent expert for project reviewing for 7 countries and organizations. He graduated at University of Science and Technology, Beijing, got PhD at Stockholm University, and worked as a postdoctoral fellow at University of Windsor. He has published more than 200 papers, two books and three chapters/overviews in three books, and delivered more than 60 plenary, keynote and invited lectures at different international conferences. He received the Howard F. Taylor Award of the American Foundryman’s Society in 1992 and was the nominees for the “Kami Prize” between 2012-2015, and the Wilhelm Haglund Medal 2016 and 2019. Several advanced materials such as Sanicro 25, Hyper duplex stainless steels, advanced martensitic stainless steels (Highflex and Freeflex), HEA Ni based alloys and other Sandvik grades/Alleima have been developed. He was the conference organizer for several international conferences.

报告人单位：1. Linköping University, Sweden, 2. Alleima AB, Sweden

报告时间：2023-11-14 15:00

报告地点：材料B楼520

主办单位：上海大学

联系人：王博