摘要
采用新型高性能TiB2陶瓷微粉体,以Al粉作为粘结相,通过Nd∶YAG激光表面合金化工艺,对耐热、高强Mg-Gd系变形镁合金进行了表面激光合金化处理。利用SEM、XRD、TEM、显微硬度仪、摩擦磨损试验机和ZahnerIM6ex型电化学工作站分别对不同TiB2含量合金化层的精细结构、物相、耐磨及耐蚀性能等进行了检测和分析。结果表明,合金化层中Al元素与镁合金基体中的Gd、Y等元素产生了原位反应,生成了高温硬质相Al2Gd和Al2Y等金属间化合物,且强化相TiB2未发生分解;原位合成的金属间化合物尺寸为100nm左右,强化相TiB2粒度为200nm左右,强化相与基体相容性良好,呈均匀分布,但分布特点和结构差异显著;合金化层整体显微硬度提高达4～6倍,且随着TiB2含量增多而增大;摩擦因数和磨损质量损失却表现出了相反的变化趋势;在一定配比范围内,激光表面合金化处理能有效改善镁合金的耐蚀性能。
A pulsed Nd∶YAG laser was used to modify the surface properties of heat-resistant and high-strength Mg-Gd wrought magnesium alloys with precursor of TiB2 ceramic micro powders and Al powders as the binders. The samples were prepared with different compositions of the precursor in order to understand the effect of TiB2 on the alloying coating. The micro-fine structure, phases constituent and micro-hardness, wear and corrosion resistance of the laser-alloyed layer with different TiB2 content were characterized by SEM （scanning electron microscope）, XRD（X-ray diffraction）, TEM, micro-hardness tester, abrasion testing machine and the Zahner IM6ex electrochemical workstation, respectively. The results show that the in-situ reaction occurs in the alloyed layer between Al and elements of Gd and Y in Mg alloy matrix, and the intermetallic compounds such as Al2Gd and Al2Y with excellent high temperature stability are generated. Meanwhile, the absence of the decomposition of the strengthening phase TiB2 can be observed. The particle size of in-situ synthesized intermetallic compounds and the reinforced phases is about 100 nm and 200 nm, respectively, and they exhibit good compatibility and uniform distribution. However, significant difference in the characteristics of distribution and structures are observed. The overall micro-hardness of the alloyed layer is increased with the increase of TiB2 content and improved up to 4~6 times of the substrate. However, the friction coefficient and wear weight loss indicate the opposite variation tendency. Compared with the magnesium alloy substrate, the corrosion resistance of the laser surface alloyed samples is improved significantly within a certain range of the composition ratio.
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2012年第11期1070-1073,共4页
Special Casting & Nonferrous Alloys
关键词
镁合金
激光表面TiB2合金化
精细结构
性能
Magnesium Alloy
Laser Surface Alloying with TiB2
Fine Structure
Properties
