12月24日（周三）名师讲坛： MAX相—热稳定，氧化和力学行为
北京交通大学“与大师面对面”名师讲坛系列活动
（机电学院，2014年秋季第14周）
MAX相: 热稳定，氧化和力学行为
【主讲人】：It. Meng. Low 教授，澳大利亚科廷大学
【时 间】：2014年12月24日（星期三）上午10：20-12：00
【地 点】：机电学院大会议室（机械工程楼Z802B）
【主 办】：研究生工作部
【承 办】：机电学院
【主讲人简介】：
Prof. It-Meng (Jim) Low, is now working at Curtin University, Australia. He was appointed to be a professor in 2011 at Curtin University. He was a leader of composites research group at Curtin, an elected fellow of the Australian Ceramic Society, and an editorial board for Journal of Ceramics.
His main research interests include synthesis and characterization of MAX phases, UHTCs, advanced ceramics and composite materials for the past 20 years. Recently, he has initiated new research projects relating to Sol-gel derived UHTCs, Nanostructured TiO2 and ZnO for energy harvesting and sensor applications, MXene materials for energy storage.
He obtained over 7 million dollars from the ARC, AINSE, DEST, CSIRO, State Government, Curtin University, ISIS, ASRP, etc. He gave more than 20 Keynote/ Invited Lectures at the international meetings.
He has published over 250 archival research papers, books and book chapters. Citations are over 1895, and H-index is 23 with an average over 7 citations per paper.
It-Meng (Jim) Low，2011年受聘于澳大利亚科廷大学教授一职，现任科廷大学复合材料研究小组组长，澳洲陶瓷学会理事，Journal of Ceramics期刊编委等职。
他主要在包括MAX相材料的合成和物相分析，超高温陶瓷材料，先进陶瓷及其复合材料等方面研究超过20年。近来，他开始专注于通过溶胶-凝胶法制备超高温陶瓷、纳米结构的TiO2和ZnO等材料用于能量收集和传感器方面的应用，以及制备剥离MAX相中间层A后得到的MXene材料在能量存储方面的应用等。
Low教授从诸多组织和机构，包括ARC, AINSE, DEST, CSIRO，州政府，科廷大学，ISIS, ASRP等获得了累计超过700万美元的科研经费资助。他还在各类国际会议上做过超过20场次的主题和邀请报告。
他发表和编著的各类文献研究论文、专著和专著章节超过250篇。被索引次数超过1895次，并且有23篇高因子文献，平均每篇被引次数超过7次。
【讲座简介】：
Mn+1AXn phases are remarkable materials and their characteristics in terms of thermal stability, oxidation behaviour and mechanical properties are described in this talk.
The susceptibility of MAX phases to thermal decomposition at 1000-1600°C in high vacuum has been studied using in-situ neutron diffraction. Above 1400°C, MAX phases decomposed to binary carbide (e.g. TiCx) or binary nitride (e.g. TiNx), primarily through the sublimation of A-elements such as Al or Si, which results in a porous surface layer of MXx being formed Positive activation energies were determined for decomposed MAX phases with coarse pores but a negative activation energy when the pore size was less than 1.0 μm. The kinetics of isothermal phase decomposition at 1550 °C was modelled using a modified Avrami equation. An Avrami exponent (n) of < 1.0 was determined, indicative of the highly restricted diffusion of Al or Si between the channels of M6X octahedra. The role of pore microstructures on the decomposition kinetics is discussed. The insights for tailor-design of MAX phases with controlled thermal stability and intercalated MXenes for energy storage are addressed.
Mn+1AXn相是一种结合了多种优异性能的材料，尤其在其热稳定性、氧化行为以及机械性能等方面表现很特别。
通过使用原味中子衍射技术对MAX相在高真空1000-1600°C温度下的热解敏感度进行分析。在温度超过1400°C后，MAX相分解二元碳化物（TiCx等）或者二元氮化物（TiNx等），首先通过A位元素的升华作用，诸如Al或Si，进而导致表面出现了多孔层状结构MXx，同时在粗孔处产生正激活能从而驱使MAX相的分解，而在孔径较小时（小于1.0 μm）会产生负激活能。使用一套改进的阿夫拉米方程组对材料在1550°C时的等温相解动力学建模分析。通过得到的一个(n) < 1.0的阿夫拉米指数来说明Al或Si元素在正八面体通道中的高度受限扩散现象。此外还将对空洞结构对物相分解动力学中所扮演的角色进行探讨。通过设计得到可控热稳定性的MAX相材料以及夹层的MXenes可存储材料也已经被开发出来。