【摘要】 高铁镁砂中引入质量分数为3%的板状刚玉（粒径为2³ mm）,经1580℃烧结制备MgO-Al₂O₃-FeOn复相材料。对烧后试样进行蠕变温度分别为1300℃、1400℃和1500℃（压力为0.2 MPa,保温时间为50 h）的压蠕变实验。试样在1300℃、1400℃和1500℃的蠕变率分别为-0.382%、-1.140%和-4.348%。在50 h的压蠕变试验中,前20 h为初始蠕变阶段,蠕变方程符合y=A+B*exp（C*x）;后30 h为稳态蠕变阶段,蠕变方程符合y=D+E*x,式中y--蠕变率,%;x--时间,h;A、B、C、D、E--实验常数。采用XRD和SEM分析表征蠕变后试样的物相组成及显微结构。结果表明:在高铁镁砂中铁氧化物的促进下,板状刚玉周围形成了镁铁铝尖晶石固溶体,并具有明显的"核-壳"环带结构。由于选用的板状刚玉粒径为2³ mm,经过不同温度的蠕变后,试样仍保持完整的环带结构而未被破坏,但由于离子扩散的原因,从外到内形成了多层环带结构。更多还原

【Abstract】 The specimens of MgO-Al₂O₃-Fe Oncomposite materials were made from both iron-rich magnesia and tabular corundum（ particle size is 2-3 mm） of 3%（ in mass fraction）,sintered at1580℃. Compressive creep of sintered specimens were measured over a temperature range of 1300-1500℃,compressive stress of 0. 2 MPa,and time of 50 h. Creep deformation rate at 1300 ℃,1400 ℃ and1500 ℃ is-0. 382%,-1. 140% and-4. 348% respectively. In 50 h compressive creep test,testing duration of 0 20 h is a primary stage and creep equation is in accordance with y = A + B* exp（ C* x）;testing duration of 20-50 h is a steady-state stage and creep equation is in accordance with y = D + E* x,where y--creep rate,%; x--time,h; A,B,C,D,E--experimental constant. The composition and microstructure of the specimens after creep were determined by X-ray diffraction and scanning electron microscopy respectively. The results show that magnesium-iron-aluminum spinel solid solution were formed around tabular corundum with the promotion of iron oxides in iron-rich magnesia,and showed a significant " core-shell" structure. Because particle size of tabular corundum is 2-3 mm,sample structureremained intact in the creep test at different temperature. Due to the ions diffusion,a multi-layer ring structure were formed from the outer to the inner.更多还原