时效对Sn、Bi微合金化的新型无铅易切削AI—Mg—Si合金的组织与性能影响

采用力学性能测试、X射线衍射物相分析、SEM观察研究了时效对固溶-冷拉处理后的Sn、Bi微合金化的新型无铅易切削6xxx系Al-Mg—Si合金棒材微观组织和力学性能影响，并比较了该合金与6262合金的切削性能。结果表明：其最佳的时效热处理工艺为170℃／10h，在此工艺磐件下，抗拉强度为348MPa，屈服强度为339MPa，延伸率为12．5％。峰时效态合金的物相组成为Al基体，主要强化相Mg2Si，低熔点物质Mg2Sn、Mg3Bi2和Bi及少量的CuAl2相。切削性能试验表明，用Sn和Bi微合金化6xxxAl-Mg—Si合金的切削性能比Pb和Bi微合金化的传统6262合金稍好。     

可加工微晶玻璃的微结构及其强韧化机理研究进展

对国内外可切削微晶玻璃的微观结构、可切削机理及强韧化机理的研究现状进行了综述。介绍了相互交联的卡片状和“卷心菜”状微观结构特征,讨论了其各自的优点及局限性。并就该新材料今后的发展趋势提出了作者的观点。     

Influence of magnesia on the structure and properties of MgO-Al2O3-SiO2-F glass-ceramics

Effects of MgO content (13.4–31.4 mol%) on the structure and properties of MgO-Al₂O₃-SiO₂-F⁻ glass-ceramics were investigated by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), infrared spectrophotometry (IR) and scanning electron microscopy (SEM). Results show that the main units of glass network structure are [SiO₄] and [AlO₄]. MgO contributes to the weakening of silica network and reduce the stability of glass structure. The main crystals of the MgO-Al₂O₃-SiO₂-F⁻ glass-ceramics are phlogopite, spinel, flur-pargrasite and forsterite. The increase of reheating temperature and MgO content are beneficial to the separation of phlogopite crystal, and cause an higher aspect ratio of the phlogopite phase, which improves the machinability of the glass-ceramics. Excellent machinability is obtained when MgO content is 31.4 mol% at the processing temperature of 1100 °C for 2 h.