【作者】 陈静；

【导师】 丁桦；

【作者基本信息】 东北大学 ， 材料加工工程， 2009， 硕士

【摘要】 氢处理是钛合金特有的一种热处理技术,它利用氢的可逆合金化作用,将氢作为临时性元素加入到钛合金中,可以达到改善钛合金组织的目的。对钛合金进行氢处理,能够改善其加工及使用性能。本文通过金相观察、X射线衍射分析、透射电镜分析、宏观硬度测试等实验方法对在750℃下置氢再经700℃除氢的TC4合金进行研究。观察了不同置氢量下除氢试样的微观组织,研究了氢处理过程中发生的相变,分析了氢处理使钛合金组织细化的机理,并且得到了除氢试样的宏观硬度与原始置氢量之间的关系。另外,通过热力学计算获得了置氢时环境氢压与钛合金内部氢含量的关系,并模拟了置氢除氢过程中H的扩散。取得的研究成果如下：(1)经置氢除氢处理后的TC4合金中有两种组织,一种是初生α相,另一种是β转变组织：β转变组织仅由α和β两相组成。置氢除氢处理通过降低初生α相体积分数、细化初生α相、细化β转变组织等途径细化合金组织。(2)随着置氢量的增加,除氢后TC4合金的宏观硬度增加。(3)钛合金置氢后,氢含量XH、置氢时的环境氢压PH2和Ti-H相互作用能I三者具有以下关系：pH2=XH2·pθ/exp[333192-2(1-XH)2I/973R]结合上式,并对Ti-H相互作用能I进行拟合,得到了置氢系统达到平衡时,合金内部氢含量与环境氢压的关系曲线。(4)尺寸为30mm×10mm×2mm的钛合金试样置氢900s后,其中心点的氢浓度可达到目标氢含量的99.85%；置氢后的试样除氢1800s后,试样内部最高氢浓度为6.67×10-3ppm。更多还原

【Abstract】 Hydrogen treatment (HT) is a peculiar heat treatment approach of titanium alloys. HT, or the use of hydrogen as a temporary element by using the reversible function, can modify the microstructure of titanium alloys. The processability and service performance will be enhanced after HT.The TC4alloy after HT (hydrogenation at750℃, and then dehydrogenation at700℃) has been investigated by optical microscope (OM), X-ray diffraction (XRD) and transmission electron microscope (TEM). The microstructures after dehydrogenation of the specimens with different hydrogen contents have been observed. The phase transformation during hydrogen treatment has been studied. The refining mechanisms of microstructure after HT have been analysed. The relationship between hardness of hydrogenation specimens after dehygenation and hydrogen content has been gained. Furthermore, the relationship between hydrogen pressure and hydrogen content of titanium alloys in the process of hydrogenation has been calculated by thermodynamic calculation, and the diffusion processes of hydrogen during hydrogenation and dehydrogenation have been simulated. The main results are as follows:(1) There are two kinds of microstructure in TC4alloy treated by hydrogenation and dehydrogenation, one is primary a phase, and the other is β transformed microstructure which is composed of a and β phase. The microstructure of TC4alloy is refined after hydrogenation and dehydrogenation which is a result of decrease of volume fraction of primary a phase, refinement of primary a phase, refining of β transformed microstructure.(2) The hardness of hydrogenated TC4after dehydrogenation increases with hydrogen content increasing.(3) The relationship among hydrogen content XH, hydrogen pressure pH2and interaction energy Ⅰof Ti-H can be expressed as follows: pH2=XH2·pθ/exp[333192-2(1-XH)2I/973R]Combining the equality above,the plot of hydrogen content in titanium alloy VS. hydrogen pressure is obtained in balanced system of hydrogenation by regression of interaction energy I.(4)After hydrogented for900s,the center hydrogen content of titanium alloy specimen with a size of30mm×10mm×2mm reaches99.85％of the target hydrogen content,after dehydrogented for1800s,the highest hydrogen content is6.67×10-3ppm.更多还原