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将SiO2颗粒填入AZ61镁合金基体上预先开出的沟槽中,利用搅拌摩擦工艺(FSP)成功地将颗粒均匀地搅拌进镁合金中。利用扫描电镜(SEM)观察了试样搅拌区颗粒分布情况,分别对高温退火和高温拉伸试样的晶粒长大情况进行了观察,测量了试样搅拌区及其附近区域的硬度,利用扫描电镜进行了断口形貌分析并对试样高温变形机制进行了分析。结果表明:大部分SiO2颗粒被均匀地搅拌进镁合金中,仅有少量的颗粒以聚集块形式存在;未掺入SiO2颗粒的搅拌摩擦试样搅拌区平均硬度为HV78,而掺入SiO2颗粒的试样搅拌区平均硬度为HV110,提高了HV30左右;合金中的SiO2颗粒有效地抑制了静态退火、高温拉伸和搅拌摩擦过程中的晶粒长大,使其保持在3μm以内;试样在400℃下以3×10-1s-1的应变速率拉伸得到的伸长率最大,达到了453%,实现了材料高应变速率下的超塑性。
The SiO2 particles were filled into the grooves pre-formed on the AZ61 magnesium alloy substrate, and the particles were successfully stirred into the magnesium alloy by the friction stir process (FSP). The distribution of the particles in the stirring zone was observed by scanning electron microscopy (SEM). The grain growth of the samples at high temperature annealing and high temperature tensile testing were observed. The hardness of the sample stirring zone and its vicinity were measured. The morphology of the fracture surface was analyzed by SEM, and the mechanism of high temperature deformation was analyzed. The results show that most of the SiO2 particles are uniformly mixed into the magnesium alloy, and only a small amount of particles exist in the form of aggregates. The average hardness of the stirring zone without HVS particles is HV78. The average hardness of the sample agitation zone is HV110, increased about HV30; SiO2 particles in the alloy effectively inhibit the grain growth during static annealing, high temperature stretching and friction stir to keep within 3μm; At 400 ℃, the elongation at the strain rate of 3 × 10-1s-1 reaches the maximum, reaching 453%, which realizes the superplasticity under the high strain rate of the material.