M. Abo-Elsoud
材料科学技术（英文）
The novel nanostructure of Al and Al{Fe were prepared by ball milling alumina with elemental Fe. The kinetics and nanostructure dependence of high temperature low stress Newtonian creep of Al and Al-0.3%Fe have been investigated and compared with the predications of the Nabarro{Herring (N-H) theory of directional diffusion. A simple theory based on the climb controlled generation of dislocations from a fixed density of sources is developed to explain the observed behavior. The dislocation density increases and subgrains form during the creep. Also, the presence of precipitates of FeAl3 reduces the creep rate of Al by absolute faster of 100 at the same stress and temperature, in spite of the fact that the grain size in the Al-0.3%Fe alloy is smaller by a factor of about 100 nm. The reduction of grain size to the nanometer scale improves their mechanical properties. Electron diffraction methods combined with transmission electron microscopy (TEM) and scanning electron microscopy (SEM) studies are a convenient and powerful technique for the characterization of the phases and grain structure of the resulting materials.
关键词:
Ball milling
Ruijing ZHANG
,
Ke YANG
,
Tianying XIONG
材料科学技术（英文）
Nano-SiO2 with high activity and mesopores was prepared through sol-gel synthesis followed by low-temperature heat treatment and ball milling firstly in our experiments. TEM was performed to measure particle sizes. Nitrogen adsorption experiments were carried out to estimate specific surface area, porous distribution and porous ratio by BET and BJH methods. The content of Si-OH in SiO2 surface was calculated by analysis of the results of hydrogen-oxygen content mensuration (HOCM). As a result, appropriate heat treatment system and ball milling time are important to preparation for nano-SiO2 with high activity and mesopores, which are 5~50 nm particles, 5~6 nm average aperture, 85%~93% porous ratio, and 51%~55% Si-OH content in surface. Nano-SiO2 with that structure has high surface energy and activity. This process, which has simple facilities and operation rules, is a new way of preparation for nano-SiO2 with high activity and mesopores.
关键词:
Heat treatment
,
null
,
null
,
null
新型炭材料
doi:10.1016/s1872-5805(12)60010-9
采用机械合金化技术制备高分散多壁碳纳米管( MWCNTs) -铝(Al)复合材料.将纯度99％的铝粉和质量分数2％的MWCNTs经超声和水平球磨处理使Al颗粒与MWCNTs间产生机械键合力.场发射SEM观察表明,MWCNTs分散在Al薄片的表面,随球磨时间的不同,颗粒大小和形貌各异.采用加压烧结手段将混合粉末加工成块体材料,其微观硬度测试表明,加入MWCNTs后Al基体的机械性能得到提高.
关键词:
多壁碳纳米管
,
金属基体复合材料
,
球磨
