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研究热挤压Al5083/B_4C纳米复合材料的显微组织表征和力学行为。Al5083和Al5083/B_4C粉末在氩气气氛和旋转速度400 r/min条件下球磨50 h。为提高伸长率,将球磨粉末与30%和50%(质量分数)平均粒径>100μm和<100μm未球磨粉末进行混合,然后进行热压和热挤压,挤压比为9:1。采用光学显微镜、扫描电子显微镜、能谱、透射电子显微镜、拉伸和硬度测试研究了热挤压合金。结果表明,机械球磨和B_4C颗粒使Al5083合金的屈服强度从130 MPa提高至560 MPa,但伸长率急剧下降(从11.3%降至0.49%)。添加平均粒径<100μm未球磨颗粒可提高合金的塑性但降低拉伸强度和硬度,而添加平均粒径>100μm未球磨颗粒同时降低拉伸强度和塑性。随着未球磨颗粒含量的增加,断裂机理从脆性断裂转变为韧性断裂。
The microstructural characterization and mechanical behavior of hot extruded Al5083 / B_4C nanocomposites were investigated. Al5083 and Al5083 / B_4C powders were ball milled for 50 h under an argon atmosphere at a rotating speed of 400 r / min. In order to increase the elongation, the milled powders were mixed with 30% and 50% (mass fraction) of non-milled powders having an average particle size of> 100 μm and <100 μm and then hot-pressed and hot-extruded at a compression ratio of 9: 1. The hot extrusion alloy was investigated by optical microscope, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, tensile and hardness testing. The results show that mechanical milling and B_4C particles increase the yield strength of Al5083 alloy from 130 MPa to 560 MPa, but the elongation decreases sharply (from 11.3% to 0.49%). Addition of non-milled particles with an average particle size of <100 μm can improve the plasticity of the alloy but reduce the tensile strength and hardness while adding non-milled particles with an average particle size> 100 μm while reducing tensile strength and plasticity. The fracture mechanism changes from brittle fracture to ductile fracture with the increase of the content of un-milled particles.