【作者】 王倩；

【导师】 赵骧； 吴艳；

【作者基本信息】 东北大学 ， 材料学， 2018， 硕士

【摘要】 核聚变发电是21世纪正在研究中的重要技术,与核裂变相比,热核聚变不但资源无限、易于获得,其安全性也是核裂变反应堆无法相比的。核聚变装置的包层结构材料为低活化钢,其服役环境为强磁场和高温,这种极端服役条件可以显著影响钢的服役寿命。合金碳化物的析出强化是钢中主要强化方式之一,碳化物析出相的长大、粗化、溶解或消失将会使钢的高温蠕变强度大幅降低。而合金碳化物的形核和演变离不开合金原子的扩散,所以研究强磁场与高温共同作用下合金碳化物形成元素的扩散对于提高合金钢在极端条件下的使用寿命和力学性能以及利用强磁场开发新型耐热钢具有重要的理论指导意义。本文选用纯Fe和纯Cr、V、Mo、W为实验材料,利用金相显微镜、电子探针、扫描电镜等手段研究了强磁场下Fe-Cr、Fe-V、Fe-Mo、Fe-W扩散偶在纯Fe的不同相区的固态扩散行为。利用Boltzmann-Matano(俣野)方法计算了有无磁场作用下扩散偶中各扩散组元的互扩散系数。强磁场作用下Fe-Cr扩散偶的固态扩散行为的研究结果表明:在纯Fe的奥氏体相区退火时,强磁场抑制了 Fe、Cr原子的互扩散,使Cr原子在纯铁中的扩散距离和扩散系数明显减小。在顺磁性铁素体相区和铁磁性铁素体相区退火时,强磁场促进了 Fe、Cr原子的互扩散,使Cr原子在纯铁中的扩散距离和扩散系数明显增加。在三个不同的相区,施加磁场对相同相区扩散层的相组成均没有显著影响。强磁场作用下Fe-V扩散偶的固态扩散行为的研究结果表明:在三个不同相区基本没有发生Fe、V原子的互扩散,而主要以碳发生扩散生成钒的碳化物为主。施加磁场均促进了钒碳化物的生成,特别是在顺磁性铁素体相区和铁磁性铁素体相区,这种促进作用更明显。施加磁场没有改变相同相区扩散层中钒碳化物的种类。强磁场作用下Fe-Mo扩散偶的固态扩散行为的研究结果表明:在Fe的奥氏体相区和在顺磁性铁素体相区,施加磁场抑制了 Fe、Mo原子的互扩散,使Mo原子在纯Fe中的扩散距离和扩散系数减小。在Fe的铁磁性铁素体相区退火中基本没有发生Fe、Mo原子的互扩散,而主要以C发生扩散生成钼碳化物为主。在三个不同的相区,施加磁场均没有明显改变相同相区的扩散层的相组成。强磁场作用下Fe-W扩散偶的固态扩散行为的研究结果表明:对Fe-W扩散偶,在Fe的奥氏体相区和顺磁性铁素体相区退火时,施加磁场抑制了 Fe、W原子的互扩散,使W原子在纯Fe中的扩散距离和扩散系数明显减小。在Fe的铁磁性铁素体相区退火中基本没有发生Fe、W原子的互扩散,而主要以C发生扩散生成钨碳化物为主。在三个不同的相区,施加磁场均没有明显改变相同相区的扩散层的相组成。更多还原

【Abstract】 Nuclear fusion power generation is an important technology which is researching during 21st century.Compared with the nuclear fission,thermonuclear fusion is not only easy to obtain resources,but also much safer than nuclear fission reactors.The cladding structure material of nuclear fusion device is low-activated steel,its service environment is high magnetic field and high temperature,and this extreme conditions can significantly affect the service life of the steel.One of the main strengthen ways in steels is precipitation strengthening.of alloy carbides,the growth,coarsening,dissolution or disappearance of precipitation phases can significantly reduce high temperature creep strength.The nucleation and evolution of carbides can not be separated from the diffusion of alloy atoms.Therefore,researching the diffusion behavior of carbide forming elements in different phase regions of pure iron under the combined action of high magnetic field and high temperature has important theoretical significance to improve service life and mechanical property of alloy steels under extreme conditions.In this paper,by means of optical microscope,electronic microprobe analyzer,scanning electronic microscope etc,the solid diffusion behavior of Fe-Cr,Fe-V,Fe-Mo and Fe-W were researched with and without high magnetic field.Boltzmann-Matano plane solution method was used to calculate the diffusion coefficient of the diffusion couple.The results of solid state diffusion behavior of Fe-Cr diffusion couple under high magnetic field show that the high magnetic field suppresses the interdiffusion of Fe and Cr annealing in the austenite phase of pure Fe,decreases diffusion distances and diffusion coefficient of Cr in Fe obviously.Annealing in the paramagnetic ferrite phase and ferromagnetic ferrite phase,strong magnetic field promotes the interdiffusion of Fe and Cr,increases the diffusion distance and diffusion coefficient of Cr atoms in pure iron significantly.Magnetic field has no significant effect on the phase composition of the diffusion layer in the same temperature region.The results of solid state diffusion behavior of Fe-V diffusion couple under high magnetic field show that there is almost no interdiffusion of Fe and V atoms in the three different phase regions.The acceleration effect of magnetic field on the formation of vanadium carbides is more pronounced in the paramagnetic ferrite phase region and the ferromagnetic ferrite phase region.The applied magnetic field did not change the species of vanadium carbide in the diffusion layer of the same phase.The results of solid state diffusion behavior of Fe-Mo diffusion couple under strong magnetic field show that the magnetic field inhibits the inter-diffusion of Fe and Mo atoms in the austenite phase region of Fe and in the paramagnetism ferrite phase region,decreases the diffusion distances and diffusion coefficient of atoms in pure Fe.During paramagnetism ferrite phase zone annealing,there was almost no mutual diffusion of Fe and Mo.In three different phase regions,the applied magnetic field do not significantly change the phase composition of the diffusion layer in the same temperature range.The results of the solid-state diffusion behavior of Fe-W diffusion couple under strong magnetic field show that annealing in the austenite and paramagnetic ferrite region of Fe,magnetic field inhibits the diffusion of Fe and W.decreases the diffusion distance and diffusion coefficient of W atoms in pure Fe obviously.During annealing in the ferromagnetic ferrite phase of Fe,there was almost no mutual diffusion of Fe and W atoms.In three different phase regions,magnetic field did not significantly change the phase composition of the diffusion layer in the same temperature.更多还原