【2018-0326】搅拌铸造法制备短碳纤维/AZ91复合材料的组织与性能

《复合材料学报》优先在线发表论文。

摘  要：采用搅拌铸造法制备了三种体积分数（10vol%、15vol%、20vol%）的短碳纤维增强镁基复合材料（CFs/AZ91），并选取了三个挤压比和两个挤压温度对其进行热挤压变形，采用光学显微镜（OM）、SEM和TEM对CFs/AZ91复合材料的显微组织进行了观察，并测试其室温力学性能及阻尼性能。研究结果表明，热挤压能够有效降低CFs/AZ91复合材料气孔率；在热挤压过程中，纤维沿挤压方向定向排列同时基体发生动态再结晶。随着挤压温度以及挤压比的增大，晶粒呈现等轴状，组织更加均匀。CFs/AZ91复合材料经过挤压后，其力学性能得到提高，屈服强度和抗拉强度随挤压比和CFs体积分数的增大而增大，然而CFs纤维在热挤压后发生明显断裂，这限制了挤压态复合材料强度的进一步提升。低温低挤压比条件下，CFs/AZ91复合材料具有较好的阻尼性能，随着挤压比以及挤压温度的升高，复合材料室温以及高温阻尼性能均有所降低。

关键词：搅拌铸造；热挤压；CFs/AZ91；镁基复合材料；显微组织；力学性能

Abstract: Three kinds of short carbon fiber (CFs) reinforced AZ91 Mg matrix composites with different CFs volume fractions (10vol%, 15vol%, 20vol%) were fabricated by stir-casting method. The cast CFs/AZ91composites were extruded into bars with three different extrusion ratios at 250℃ and 350℃, respectively. During the hot extrusion, grains of the AZ91 matrix are refined due to the dynamic recrystallizaiton while the CFs fiber distributed parallel to the extrusion direction. With increasing of the extrusion temperature and extrusion ratio, the porosity ratio of the CFs/AZ91composites are reduced effectively and the recrystalled grains grew up accompanied by the improvement of the microstructure homogeneity. The tensile properties of CFs/AZ91 composites are improved due to the improved microstructure whereas the fiber fractured obviously during extrusion, which would restrict the further improvement of the mechanical properties. The CFs/AZ91composite extruded with small extrusion ratio at lower temperature has better damping capabilities than those of the composites extruded with high extrusion ratio and higher temperature.

Keywords: stir-casting; CFs/AZ91; Mg matrix composites; extrusion; microstructure; mechanical properties

作者：常海等，北京科技大学 材料服役安全科学中心，北京

通讯作者：胡小石，哈尔滨工业大学 材料科学与工程学院，哈尔滨

全文详见中国知网学术期刊优先数字出版。