α-Fe晶界的力学行为及缺陷效应

发布时间：2017-12-27 22:37

本文关键词：α-Fe晶界的力学行为及缺陷效应　出处：《上海工程技术大学》2016年硕士论文　论文类型：学位论文

【摘要】：α-Fe以其优异的抗辐照肿胀和抗腐蚀性能被认为是聚变堆第一壁结构材料最具吸引力的候选之一。作为反应堆器壁材料,核聚变反应中产生的嬗变产物氦进入材料内部,与材料中的晶界、空洞等缺陷相互作用导致材料微观结构发生变化,引起辐照硬化、韧脆转变温度升高和体积膨胀等问题,直接影响聚变堆运行的可靠性,给核反应堆的安全性提出了严峻的挑战。本课题借助分子动力学方法对α-Fe不同倾侧晶界在不同温度、空洞位置、He原子分布浓度等条件下进行模拟分析,研究α-Fe不同倾侧晶界的力学行为,分析纳米空洞、He原子等缺陷对晶界力学行为产生的影响。首先分析了α-Fe不同倾侧晶界的力学性能,发现晶界的断裂应力、断裂应变和弹性模量与取向角度有关;随温度升高,晶界的断裂应变和弹性模量逐渐降低。其次模拟了含缺陷时晶界的拉伸加载过程,分析He原子缺陷对晶界力学行为的影响,对比不同He原子分布浓度、温度、空洞位置条件下原子演变过程。结果发现:He团簇随应变增加挤出附近晶格上的Fe原子形成氦-空位团,并相互扩散连接形成微裂纹导致晶界断裂;随He原子分布浓度增加其晶界断裂由塑性断裂转变为脆性断裂;空洞位置对晶界中He原子演变过程有很大影响。最后分析α-Fe含空洞缺陷的∑5{310}100晶界模型在拉伸加载过程中位错的萌生增殖机理,结果表明:空洞远离晶界时,空洞周围沿密排面向4个方向发射1/2111位错环;空洞位于晶界附近时,空洞远离晶界一侧发射1/2111位错环,而空洞靠近晶界一侧位错环的发射受到晶界抑制。
[Abstract]:The excellent anti radiation swelling and corrosion resistance of alpha -Fe is considered to be one of the most attractive candidates for the first wall structure material of the fusion reactor. As the reactor wall material, nuclear fusion reaction in the evolution of helium into the product inside the material, grain boundaries, and material holes in interaction leads to the microstructure of the material changes caused by irradiation hardening, ductile brittle transition temperature and volume expansion and other issues, directly affects the reliability of fusion reactor, put forward a severe challenge to the safety of nuclear reactors. This subject by means of molecular dynamics method of alpha -Fe different tilt grain boundaries in different temperature and hole position, He atom concentration distribution under the simulation analysis, the mechanical behavior of a -Fe different tilt grain boundaries, analysis of the impact of nano void and He atom defects on grain boundaries of mechanical behavior. First analysis of the mechanical properties of -Fe with different tilt grain boundaries, the grain boundary fracture stress, fracture strain and elastic modulus and orientation angle; with the increase of temperature, the fracture strain and elastic modulus of the grain boundary decreases gradually. Secondly, the tensile loading process of grain boundary is simulated, and the effect of He atom defect on the mechanical behavior of grain boundary is analyzed. The evolution process of atoms under different He concentration, temperature and void location is compared. The results showed that He clusters near the Fe atoms on the lattice extrusion forming helium vacancy clusters with increasing strain, and mutual diffusion bonding formation of microcracks leads to intergranular fracture; with the He atom concentration distribution increases the grain boundary fracture changed from ductile fracture to brittle fracture; has a great influence on the evolution of the void position in the process of He atoms at grain boundaries. The final analysis of the initiation mechanism of proliferation, sigma alpha -Fe 5{310}100 grain boundary model containing voids dislocation in tensile loading process in the cavity from grain boundary, near the hole along the close packed face 4 direction emission 1/2111 ring dislocation; voids at the grain boundaries, away from the hole side emitting 1/2111 grain boundary dislocation loops, and the hole near the grain boundary one side of the emission by inhibiting grain boundary dislocation loop.
【学位授予单位】：上海工程技术大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O614.811

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