纯钛及钛合金的强流脉冲电子束表面改性研究

发布时间：2018-10-30 21:08

【摘要】：强流脉冲电子束技术是近年来发展起来的一项新兴材料表面改性技术,而轧制是在上世纪发展起来的金属形变技术。本文将轧制技术和强流脉冲电子束技术相结合,并选择纯钛TA2及TC2、TC4钛合金进行复合处理,研究了这几种材料表层微结构、相组成、硬度和抗腐蚀性能在处理前后的变化,主要研究结果如下:1、在电子束处理过程中,纯钛和TC2、TC4钛合金表层都发生了α向β再向α’的马氏体转变。电子束处理后,纯钛及钛合金表面形成大量火山坑,而随着电子束脉冲次数的增加,火山坑密度呈现出减少的趋势。2、电子束处理也使得表层晶粒出现了择优取向,XRD分析显示α(002)、α(101)晶面衍射强度不断降低,而α(100)晶面衍射强度逐渐增强。3、轧制对纯钛及TC2、TC4钛合金起到了形变强化的作用,而电子束处理使得纯钛及TC2、TC4钛合金的表面硬度下降,主要是因为脉冲电子束处理消除了表面残余应力及生成的马氏体硬度较低的缘故。4、轧制及电子束处理能提高纯钛的抗腐蚀性能,随着变形率的增加、抗腐蚀性能逐渐增加,当轧制变形率为70%时,抗腐蚀性能最好。当纯钛变形率一定时,脉冲次数为5次时,纯钛抗腐蚀性能最好。在电子束5次脉冲处理时,随着变形率的增加,纯钛抗腐蚀性能愈来愈好,变形率为70%,电子束轰击次数为5次时,腐蚀电流密度为245.3 m A/cm2。这主要是因为轧制的大塑性变形使得纯钛晶粒得到充分细化,当脉冲次数过多时,反而引起晶粒的长大,降低纯钛的抗腐蚀性能。5、TC4钛合金在轧制加脉冲电子束处理后,材料的抗腐蚀性能大幅提高,电子束分别轰击TC4钛合金5次,10次后,自腐蚀电位较基体的-682.5m V分别增加到-297.5m V、-342.3 m V。而腐蚀电流密度也由基体的1028.1m A/cm2减少到电子束5次脉冲处理时的382.0 m A/cm2。TC2钛合金自腐蚀电位从电子束处理前的-625.7 m V升高到10次脉冲的-163.5m V,而5次脉冲处理后,腐蚀电流密度减少到了343.3 m A/cm2。表明电子束对TC4、TC2钛合金处理后,5次脉冲时抗腐蚀性能最好,晶粒细化、相组成均一化和表面净化是材料表面腐蚀性能提高的主要原因。
[Abstract]:High current pulsed electron beam technology is a new material surface modification technology developed in recent years, and rolling is a metal deformation technology developed in the last century. In this paper, the rolling technology and high current pulsed electron beam technology are combined, and pure titanium TA2 and TC2,TC4 titanium alloys are selected for composite treatment. The changes of surface microstructure, phase composition, hardness and corrosion resistance of these materials before and after treatment are studied. The main results are as follows: 1. In the process of electron beam treatment, both pure titanium and TC2,TC4 titanium alloys undergo a transformation from 伪 to 尾 to 伪 'martensite. After electron beam treatment, a large number of volcanic craters were formed on the surface of pure titanium and titanium alloys, and the density of volcanic pits decreased with the increase of the number of electron beam pulses. XRD analysis showed that the diffraction intensity of 伪 (002), 伪 (101) plane was decreasing, while the diffraction intensity of 伪 (100) plane was gradually increasing. 3. Rolling had the effect of strengthening the deformation of pure titanium and TC2,TC4 titanium alloy. However, the surface hardness of pure titanium and TC2,TC4 titanium alloy was decreased by electron beam treatment, which was mainly due to the elimination of surface residual stress and the lower hardness of martensite formed by pulsed electron beam treatment. Rolling and electron beam treatment can improve the corrosion resistance of pure titanium. With the increase of deformation rate, the corrosion resistance increases gradually. When the rolling deformation rate is 70, the corrosion resistance is the best. When the deformation rate of pure titanium is constant and the pulse number is 5 times, the corrosion resistance of pure titanium is the best. When the electron beam was treated with 5 pulses, the corrosion resistance of pure titanium increased with the increase of deformation rate. The corrosion current density of pure titanium was 245.3 Ma / cm ~ 2 when the electron beam bombardment times were 5 times and the deformation rate was 70 times. This is mainly due to the large plastic deformation of rolling, which makes the grain of pure titanium fully refined. When the pulse number is too many, the grain will grow up, and the corrosion resistance of pure titanium will be reduced. 5% TC4 titanium alloy after rolling with pulsed electron beam treatment, The corrosion resistance of the material was greatly improved. After 5 times of electron beam bombardment on TC4 titanium alloy, the self-corrosion potential increased from -682.5mV to -297.5m V ~ (-1) -342.3 MV, respectively. The corrosion current density decreased from 1028.1 A/cm2 of substrate to 382.0 m A/cm2.TC2 of titanium alloy treated by electron beam for 5 times. The corrosion potential of titanium alloy increased from -625.7 MV before electron beam treatment to -163.5m V with 10 pulses. After five pulse treatments, the corrosion current density decreased to 343.3 Ma / cm ~ 2. The results show that the corrosion resistance of TC4,TC2 titanium alloy treated by electron beam is the best after 5 pulses, the grain is fine, the phase composition is homogenized and the surface purification is the main reason for the improvement of the surface corrosion performance of the material.
【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】：2015
【分类号】：TG174.4

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