自支撑Ti/Al纳米多层膜激光诱发自蔓延行为  

LASER-IGNITED SELF-PROPAGATING BEHAVIOR OF SELF-SUPPORTING NANO-SCALED Ti/Al MULTILAYER FILMS

作　　者：安荣[1,2] 田艳红[1,2] 孔令超[2] 王春青[1,2] 常帅[2] 

机构地区：[1]哈尔滨工业大学微系统与微结构制造教育部重点实验室,哈尔滨150080 [2]哈尔滨工业大学先进焊接与连接国家重点实验室,哈尔滨150001

出　　处：《金属学报》2014年第8期937-943,共7页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目51005055;中央高校基本科研业务费专项资金项目HIT.NSRIF.2015066资助~~

摘　　要：通过磁控溅射法并借助有机高分子牺牲层，制备了具有不同调制结构的自支撑Ti／Al（调制比为1）纳米多层膜．采用脉冲激光诱发了纳米多层膜的自蔓延反应，确定了临界诱发能量密度．利用高速摄影法表征了自蔓延速度，采用SEM和TEM观察了纳米多层膜结构，利用差热分析仪和XRD分析了反应过程及产物．结果表明，纳米多层膜激光诱发临界能量密度（6～17J／cm2）高于烧蚀临界能量密度．调制周期或周期数较小的纳米多层膜激光诱发所需的能量密度较小且自蔓延速度较高．但当调制周期接近或小于层间原子互溶区厚度时，临界能量密度和自蔓延速度的变化则有相反趋势．对于一定厚度的纳米多层膜，具有大调制周期和小周期数的调制结构对应的放热量大．随激光脉冲持续时间的延长，Ti／ml纳米多层膜的激光临界诱发能量密度呈现递减趋势，但最终趋于稳定．激光诱发Ti／Al纳米多层膜自蔓延反应生成单一的TiAl金属间化合物．Nano- scaled reactive multilayer films are the attractive option for the synthesis of intermetallic compounds and for local joining applications. Reactive multilayers consist of alternating layers of reactants having a large negative enthalpy of mixing. For certain designs, these foils exhibit rapid exothermic reactions at high tem- perature. A reaction is ignited by an external energy source such as an electric spark or a mechanical load. Once ig- nited, reactions within foils can produce sufficient heat at a rapid rate to induce further layer intermixing via ther- mally induced atomic diffusion. This results in a self-propagating reaction that then envelopes the foil. Recent work igniting energetic powder mixtures has employed lasers as a means for determining the ignition temperatures and energies. Lasers provide a controllable source of energy that can be used to better quantify ignition parameters still unknown for many reactive material systems. Short-pulsed lasers, in particular, allow for controlled energy deposi- tion into a small volume. Despite a few studies of ignition, the susceptibility of exothermic nano-scaled multilayerto external pulsed laser has not been significantly explored. In this work, self-supporting Ti/AI （modulation ratio 1） multilayer films with different modulation structures were prepared by means of magnetron sputtering method and a sacrificial layer process. These films were ignited by a single pulse irradiation for their self-propagating reac- tions. The ignition fluence thresholds were determined and their microstructures were observed using SEM and TEM. Propagation rate was characterized by high speed photography. DSC and XRD were used to analyze the reac- tion processes and products. It indicated that all measured critical ignition fluences （6～17 J/cm2） are above the typi- cal ablation threshold fluences for metals under laser irradiation. With decreasing modulation period, the ignition fluence threshold decreases and the propagation velocity increases. In contrast,

关 键 词：纳米多层膜 自支撑 自蔓延 调制结构 脉冲激光 

分 类 号：TG42[金属学及工艺—焊接] O532[理学—等离子体物理]