【作者】 丰新宇；

【导师】 张罡；

【作者基本信息】 沈阳理工大学 ， 材料学， 2010， 硕士

【摘要】 强流脉冲离子束（HIPIB）与材料交互作用的基础研究具有重要的科学意义,同时强流脉冲离子束在表面工程领域有着广阔的应用前景。本论文对HIPIB辐照材料的热学效应进行了模拟,对HIPIB辐照工业纯铁和45^#钢的热力学效应进行了实验研究,获得了HIPIB表面改性的机理及控制规律,为HIPIB的工程应用提供了依据。系统论述了HIPIB热力学效应模拟和辐照机理等研究方向的进展。采用SRIM程序模拟了C⁺、H⁺离子对铁靶的注入作用。运用有限元工程模拟软件ABAQUS,采用体加载、单元死活算法和能量沉积耦合等方式,模拟了HIPIB辐照GH3030、45^#钢和TC4钛合金的热效应。模拟结果表明:辐照离子能量相同时,H⁺离子的射程大于C⁺离子;离子的注入在靶材亚表层产生了大量缺陷（vacancies）;50ns脉冲时间内,45^#钢靶材表面的升温速率可达8.8×10¹⁰℃/s;辐照结束后,45^#钢靶材表面液相冷却速率达可1.4×10¹⁰℃/s。利用TIA-450型HIPIB设备对工业纯铁和45^#钢进行了表面辐照实验,典型实验参数为:束流组成70%C⁺+30%H⁺,脉冲宽度50ns,二极管加速电压400kV,束流密度170-200A/cm2。通过对辐照次数分别为1、5、10、20的系列实验,系统地研究了随脉冲次数增加,靶材表面形貌及组织结构的演变过程及规律。采用扫描电镜（SEM）、显微硬度仪、X射线衍射仪（XRD）和透射电镜（TEM）等方法对靶材表面形貌、相结构、显微硬度及微观组织进行了检测,研究结果表明: HIPIB辐照使靶材表面发生了快速熔化及凝固,辐照表面形成了熔坑;后续辐照对先前产生的熔坑有模糊化甚至消除的趋势;亚表层局部区域的爆破式喷发是形成熔坑的主要原因。HIPIB辐照使工业纯铁靶材表面硬度呈提高趋势;随着辐照次数的增加,硬度提高的趋势逐渐减缓;HIPIB辐照对工业纯铁靶材的作用以塑变硬化为主;1次辐照后,淬火45^#钢靶材表面显微硬度提高;随着辐照次数的增加,硬度呈先下降后稳定的趋势;淬火45^#钢靶材表层在多次辐照情况下发生了回复及再结晶;在爆破式喷发引起的强应力波作用下,工业纯铁和45^#钢靶材表面熔坑区的显微硬度水平高于无熔坑区。HIPIB辐照使工业纯铁靶材中的位错密度增大;随着辐照次数的增加,位错线发展成位错网、位错墙、位错胞以及亚晶界;多次辐照后,工业纯铁靶材局部区域的位错密度下降;多次辐照后,淬火45^#钢靶材中的位错密度比辐照前有所下降; HIPIB辐照使工业纯铁和45^#钢靶材表层出现了择优取向趋势,HIPIB辐照产生的应力波效应和表层液相的定向凝固可能是其成因;反复的应力波作用使组织呈细化趋势。HIPIB辐照的瞬间熔化再凝固效应使工业纯铁和45^#钢表面部分区域形成了纳米晶和非晶。本实验条件下,10-20次辐照可使工业纯铁和45^#钢的表面形貌均匀化,组织细化及非晶化;在不显著降低强度的前提下,HIPIB辐照可对淬火45^#钢实现表面组织的细化及非晶化。更多还原

【Abstract】 It is of scientific importance to study the fundamental mechanisms of interaction between materials and the high-intensity pulsed ion beam （HIPIB）, which is also an efficient tool for surface engineering. In the present work, the thermo-effects of HIPIB irradiation were simulated, the mechanisms of HIPIB irradiation were researched experimentally, some mechanisms are concluded and a few process plans are given. The results are as follow:The research results of numerical and experimental studies on the thermodynamical effects of HIPIB were reviewed. The effects of C⁺ and H⁺ implantation into iron target were simulated by SRIM code. The thermo-effects of HIPIB irradiation on GH3030, 45^# steel and TC4 were simulated. The results indicate that: The range of H⁺ ion is longer than that of C⁺ ion with the same energy; lots of vacancies would be formed in the subsurface areas of the targets as a result of the ion implantation; the heating rate of the 45^# target surface may reach 8.8×10¹⁰℃/s during irradiation; the cooling rate of the liquid phase of the 45^# target surface may reach 1.4×10¹⁰℃/s after irradiation.Ingot iron and 45^# steel sample targets were irradiated by HIPIB generated from TIA-450 accelerator, the beam parameters were: 70%C⁺+30% H⁺, pulse width of 50-80ns, accelerating voltage of 200-400kV, current density of 170-200A/cm²; SEM, XRD, TEM, etc. were applied to investigate the sample targets, the experimental results are as follow:Fast melting and resolidification occurred on the surfaces of the targets and craters were formed; craters could be blurred or diminished by successive HIPIB shots; the explosive eruption in local subsurface areas is the main cause of craters.The surface microhardness of ingot iron targets was improved by HIPIB irradiation; the hardening rate would be slowed; the ingot iron targets were strengthened by HIPIB; the surface microhardness of 45^# steel targets was improved after 1 shot and then decreased and stabilized as the shot number increases; the prequenched 45^# steel targets were annealed after multi-shots of HIPIB; the surface microhardness of the zones with craters is higher than those without crater due to the stress wave field generated by explosive eruptions.The density of dislocations in ingot iron targets were increased; dislocation nets, dislocation walls, dislocation cells and subgrains were formed as the shot number increased; density of dislocations in local areas of ingot iron targets were decreased after multi-shots of HIPIB; the density of dislocations in prequenched 45^# steel targets were relatively lower than the original state; preferred orientations were formed in ingot iron and 45^# steel targets irradiated by HIPIB, which might be caused by stress waves and directional solidification; the structures of the targets were refined by repeated stress waves.Nano-crystalline and amorphous structure were formed in local areas on surfaces of both ingot iron and 45^# steel targets by fast melting and resolidification.Under present experimental condition, the surface morphology of the samples could be homogenized and the structure could be refined or changed into amorphous state after 10-20 shots; it is possible to refine the surface structure of 45^# steel samples without decreasing the strength significantly.更多还原