学术报告：Marvelous one-dimensional dispersoids in metals: Synthesis, Toughening, Radiation tolerance
报告题目：Marvelous one-dimensional dispersoids in metals: Synthesis, Toughening, Radiation tolerance
报 告 人：Kang Pyo So 来自MIT 核工系和材料系
The actual strength of conventional bulk metallic alloys is far less than even 10% of the ideal strength. The properties of an alloy are a byproduct at simply mixing of different composition. The compositional freedom of alloys is limited by the solubility and chemical stability of each material. However, the stable nanostructured metals show superior properties compared to bulk metals. When size approaches the nanoscale, unusual properties are observed. One-dimensional (1D) nanodispersoids in metal composites could bring those nanoscale properties to the bulk scale. For example, 1D carbon nanotubes (CNTs), which are mechanically strong and flexible, possess better structural properties than their counterpart nanoparticles and other one-dimensional nanowires. We demonstrate an intragranular dispersion strategy of CNTs in Al matrix that leads to comprehensively improve the room-temperature tensile strength, toughness and high-temperature creep strength of alloys without sacrificing tensile ductility, electrical conductivity or thermal conductivity. Well-dispersed CNTs act like forest dislocations, except mobile dislocations cannot annihilate with them. Therefore it can harden the metal pretty much like stored dislocation line density, as well as still acting like a composite filler and transmitting load directly. Dislocations cannot climb over 1D CNTs, unlike 0D dispersoids/precipitates. This could allow bringing the metals to the ideal limit. Also, unlike 2D grain boundaries, even if some debonding happens along 1D CNT/alloy interface, it will be less damaging because fracture intrinsically favors 2D percolating flaws. Furthermore, percolating 1D CNT fillers create prolific internal interfaces with the metal matrix that act as venues for the radiation defects to recombine, reducing void/pore generation and radiation embrittlement under the nuclear environment. 1D dispersoids also reduce solute segregation and fission byproduct accumulation due to the intrinsic nature of its percolating network. Thus, the 1D dispersoids in metal will be a new paradigm for making high-performance structural materials beyond the design space of alloys alone.
Dr. Kang Pyo So received his Ph.D. from Sungkyunkwan University (SKKU) in Sungkyunkwan Advanced Institute of Nanotechnology (SAINT) in 2012. He was a post-doctoral fellow at Institute of new paradigm of energy science convergence in SKKU in 2012-2013. Since then, he has been a post-doctoral associate at the Department of Nuclear Science & Engineering at Massachusetts Institute of Technology (MIT). He has been working on the development of metal-carbon nanotubes (CNTs) composite especially on Al-CNTs nanocomposite for mechanically strengthened structural materials. Dr. So has been paid an attention on developing industrially scalable process of Al-CNTs composite for several years. He has applied/registered >35 technical patents. His current research interests are in the application of 1D dispersoids nanocomposites on nuclear cladding materials for the improved radiation tolerance.