The β-Si3N4 whiskers (β-Si3N4w) reinforced A1 matrix com posites were first fabricated by hot pressing, then treated through hot extrusion. The microstructure characterization dem onstrated the preferred orientation...The β-Si3N4 whiskers (β-Si3N4w) reinforced A1 matrix com posites were first fabricated by hot pressing, then treated through hot extrusion. The microstructure characterization dem onstrated the preferred orientations of both β-Si3N4w and A1 grains in the as-extruded composites. It indicated th at β-Si3N4w were aligned along the extrusion direction and A1 grains exhibited a distinct <111>ai texture. The interface betw een β-Si3N4w and A1 was in a good bonding status without voids and reaction products. Effects of extrusion process on the mechanical properties of com posites were also investigated. The results indicated the extrusion process had a prom inent strengthening effect on the mechanical properties of composites. The maxim umyield strength and ultim ate tensile strength of com posites reached up to 170 and 289 MPa, respectively, accompanied by a 12.3% elongation at fracture w hen the w hisker fraction was 15 vol.%. This im provem ent was collectively attributed to the densification of composites, the strong interface, and the preferred orientation inside composites. The yield strength of the composites reinforced with 5 vol.%β-Si3N4w corresponded well w ith the theoretical value from different strengthening mechanisms.展开更多
基金supported by National Key R&D Program of China (Nos. 2017YFB0406200, 2017YFB0703200, and 2017YFB0310400)the National Natural Science Foundation of China (No. 51501215), Shanghai Sailing Program (No. 16YF1412900)+1 种基金Science Foundation for Youth Scholar of State Key Laboratory of High Performance Ceramics and Superfine Microstructures (No. SKL201701)State Key Laboratory of New Ceramic and Fine Processing Tsinghua University (No. KF201806)
文摘The β-Si3N4 whiskers (β-Si3N4w) reinforced A1 matrix com posites were first fabricated by hot pressing, then treated through hot extrusion. The microstructure characterization dem onstrated the preferred orientations of both β-Si3N4w and A1 grains in the as-extruded composites. It indicated th at β-Si3N4w were aligned along the extrusion direction and A1 grains exhibited a distinct <111>ai texture. The interface betw een β-Si3N4w and A1 was in a good bonding status without voids and reaction products. Effects of extrusion process on the mechanical properties of com posites were also investigated. The results indicated the extrusion process had a prom inent strengthening effect on the mechanical properties of composites. The maxim umyield strength and ultim ate tensile strength of com posites reached up to 170 and 289 MPa, respectively, accompanied by a 12.3% elongation at fracture w hen the w hisker fraction was 15 vol.%. This im provem ent was collectively attributed to the densification of composites, the strong interface, and the preferred orientation inside composites. The yield strength of the composites reinforced with 5 vol.%β-Si3N4w corresponded well w ith the theoretical value from different strengthening mechanisms.
