【作者】 张晨晨；

【导师】 袁武华；

【作者基本信息】 湖南大学 ， 材料加工工程， 2008， 硕士

【摘要】 本论文采用喷射沉积工艺制备了7090/SiCp复合材料,对7090/SiCp复合材料挤压、轧制成形工艺、热处理制度以及热处理过程中的组织性能演变规律进行了研究,其结果如下:(1)研究了挤压和轧制工艺对喷射沉积7090/SiCp复合材料锭坯成形性的影响。经挤压后,复合材料组织内部形成了明暗交替的环状亮带分布,SiC颗粒沿挤压方向呈流线分布。对挤压态复合材料进行轧制成形工艺研究,结果表明:轧制工艺可以在一定程度上改善SiC颗粒的不均匀分布,并且随着变形量的增加,SiC颗粒层状分布现象有明显的改善;颗粒破碎较为严重。(2)研究了7090/SiCp复合材料较佳的热处理工艺和热处理对复合材料微观组织及力学性能的影响。结果表明7090/SiCp复合材料经过470℃/1h+490℃/1h双级固溶+120℃/28h时效后的可以获得较佳的力学性能。挤压态7090/SiCp复合材料经双级固溶时效处理后,复合材料的强度达到785Mpa,比490℃/1h固溶+120℃/28h时效后的强度提高约30MPa,而模量均可以达到100GPa以上。此时,复合材料的KIC值最大,为39.49 MPa·m1/2。晶粒较单级固溶时效处理细小,在晶界处析出相呈不连续分布状态。析出相细小、弥散分布,主要为η(MgZn2)、T(Al2Mg3Zn3)和富Cu相。另外,在SiC与基体界面结合处出现5nm左右厚度的非晶氧化层。(3)研究了热处理对7090/SiCp复合材料轧制态薄板微观组织和力学性能的影响。结果表明,复合材料轧制态薄板经过490℃/1h单级固溶+120℃/28h时效和470℃/1h+490℃/1h双级固溶+120℃/28h时效处理后,强度可接近700MPa,析出相主要为MgZn相,富Cu相、Al3Zr相以及FeAl3杂质相。(4)研究了7090/SiCp复合材料的断裂模式。结果表明,7090/SiCp复合材料的断裂是沿晶断裂和穿晶断裂兼有的混合型断裂,并且以穿晶断裂为主。经过热处理后的挤压棒材拉伸断裂主要是以SiC颗粒聚集、断裂和SiC与基体界面脱粘等机制引起的。轧制板中SiC颗粒的断裂和界面脱粘断裂的混合为复合材料薄板的主要断裂机制。更多还原

【Abstract】 The ultra high strength 7090/SiCp composite reinforced was prepared by spray co-deposition process. The extrusion and rolling technical, heat treatment technology, microstructure and mechanical properties of the heat-treated extruded composite were tested and analyzed.(1) The influence of extrusion and rolling technical of the 7090/SiCp composite was analyzed. After extrusion, and arrayed on the orientation of extrusion directionally and orderly, resulting in the feature of an obvious stripe microstructure. The rolling process improves the SiC particles stripe to some extent.(2) The heat treatment technology, microstructure and mechanical properties of the heat-treated extruded composite were tested and analyzed. The result shows that the 7090/SiCp composite exhibited good mechanical property after 470℃/1h+490℃/1h+120℃/28h heat treatments.The strength of the composite treated with 470℃/1h+490℃/1h+120℃/28h exhibited ultra high strength above785MPa,which was 30MPa higher than that of the 490℃/1h+120℃/28h-treated composite. The modulus of the two heat-treated composites was both improved above 100GPa. And the fracture toughness is the best, about 39.49 MPa·m1/2. The grain size of the composites is bigger prepared by two-stage solution than by single-stage solution. The little fine phase appears in the grain and the grain boundary isη(MgZn2)、T(Al2Mg3Zn3)and Cu-rich phase. While after two-stage solution and aging treatment, an amorphous Si-Cu-Al-O(5nm)layer occurs at the interface.(3) The microstructure and mechanical properties of rolled plates of spray co-deposited 7090/SiCp composites were tested and analyed. The results also shows that the peak-aged high strength could reach 700MPa after 470℃/1h+ 490℃/1h+ 120℃/28h heat treatments. The precipitates are MgZn、Cu-rich phase、Al3Zr phase and FeAl3 impurity phase.(4) The fracture mode of the 7090/SiCp composite was analyzed. The results shows that the fracture was the intra-intergranular and intergranular fracture. The tensile fracture is resulted from M/SiC interracial debonding and SiC particles’fracture for the extruded composite,but from A1/SiC interfaeial debonding and matrix failure for the rolled composite.更多还原