【摘要】 本文开展了粉末冶金法制备的15%SiC_p/2009Al复合材料的振动研磨实验。利用光学显微镜（OM）、扫描电镜（SEM）、表面粗糙度仪、维氏硬度计、疲劳试验机等研究了不同振动研磨工艺对材料表面形貌、表面粗糙度、表面维氏硬度、疲劳强度的影响。结果表明，振动研磨可以显著降低材料的表面粗糙度，样品原始表面加工纹路完全消失，试样表面粗糙度受研磨时间和磨料形状的共同作用，经球形磨料处理3 h的试样表面粗糙度从2.46μm下降到0.32μm，降低了87%。球形磨料和斜圆柱形磨料对试样表面维氏硬度均有所提升，斜圆柱形磨料处理后的表面维氏硬度更大，从HV 164.4增加到HV 184.4，提升了12.2%。振动研磨可以显著提升材料的表面残余压应力，未经处理的试样其表面残余应力为-55 MPa，经斜圆柱形磨料处理的试样表面残余应力为-166 MPa，提升了202%。综合实验结果，获得的最佳工艺为：使用斜圆柱形磨料，振动研磨处理3 h，最终疲劳性能为265 MPa，较未处理试样提升了10.4%。更多还原

【Abstract】 Silicon carbide particle reinforced aluminum matrix composites(Si C_p/Al), specifically 15%SiC_p/2009 Al composite prepared by powder metallurgy, are increasingly utilized in aerospace and precision engineering due to their high specific strength, specific stiffness, and dimensional stability. However, the presence of hard SiC ceramic particles within the soft aluminum matrix renders these materials difficult to machine, often leading to high cutting forces and rapid tool wear in addition to surface defects. Conventional machining processes often induce surface defects such as pits, scratches, particle fracture, and matrix tearing. These surface discontinuities act as stress concentration sites, significantly deteriorating the fatigue performance and service life of the components. Therefore, improving the surface integrity of these composites post-machining is critical. The primary objective of this study was to investigate the efficacy of vibratory finishing(vibratory grinding) as a surface strengthening and polishing treatment. The research aimed to elucidate the evolution of surface morphology, roughness, microhardness, and residual stress under different vibratory finishing parameters and to quantify the subsequent impact on the high-cycle fatigue strength of the material. 15%SiC_p/2009 Al composite specimens were fabricated using a powder metallurgy technique. To systematically evaluate the effects of the finishing process, vibratory finishing experiments were conducted using specific process variables, with a focus on the influence of processing time and the geometric shape of the abrasive media. Two distinct types of ceramic abrasives were employed: spherical abrasives and oblique cylindrical abrasives. A comprehensive characterization suite was utilized to analyze the surface integrity before and after treatment. Optical microscopy(OM) and scanning electron microscopy(SEM) were employed to observe the evolution of surface morphology and to identify the removal mechanisms of surface defects. A surface roughness tester was used to quantify the reduction in surface irregularities. The surface microhardness was measured using a Vickers hardness tester to evaluate the work-hardening effect induced by the mechanical impact of the media. Surface residual stresses were determined(typically via X-ray diffraction(XRD)) to analyze the stress state transformation in the near-surface layer. Finally, the fatigue performance was assessed using a fatigue testing machine to determine the fatigue limit of the specimens treated under the optimized process parameters compared to the untreated baseline. The experimental investigation yielded significant findings regarding the modification of surface characteristics and mechanical properties. The results showed that the vibration grinding could significantly reduce the surface roughness of the material. Vibratory finishing demonstrated a remarkable capability to improve surface topography. OM and SEM observations revealed that the original machining marks and periodic tool feed patterns on the raw samples were completely eliminated after the treatment. The surface roughness was found to be dependent on the synergistic effect of the grinding time and the shape of the abrasive media. Specifically, the spherical abrasive media proved highly effective for polishing. The surface roughness of the sample dropped to 0.32 μm from 2.46 μm, a decrease of 87%, after 3 h of spherical abrasive treatment. Both spherical and oblique cylindrical abrasives contributed to an increase in surface Vickers hardness, attributed to the plastic deformation and work hardening of the aluminum matrix surrounding SiC particles. However, the geometry of the abrasive played a crucial role in the magnitude of this increase. The surface of oblique cylindrical abrasives had a higher Vickers hardness, increasing from HV 164.4 to HV 184.4, an increase of about 12.2%. Vibration grinding could significantly increase the surface residual compressive stress of the material. The untreated specimens exhibited a relatively low magnitude of residual compressive stress at-55 MPa. Post-treatment analysis showed a substantial increase in the magnitude of the compressive stress field, which is beneficial for inhibiting the initiation and propagation of fatigue cracks by offsetting the applied tensile stress during service. Specifically, the specimens treated with oblique cylindrical abrasives achieved a surface residual stress of-166 MPa. This constituted a 202% increase over the untreated state, owing to their more intense and localized impact on the composite surface that promotes greater plastic deformation. The study established a direct correlation between the vibratory finishing parameters and the resultant fatigue life of 15%SiC_p/2009 Al composites. While spherical abrasives were superior in minimizing surface roughness, the oblique cylindrical abrasives provided a more favorable combination of surface hardening and residual compressive stress enhancement, which were critical factors for fatigue resistance. According to the comprehensive experimental results, the best process was obtained: oblique cylindrical abrasive was employed, followed by 3 h of vibration grinding. The resultant fatigue strength reached 265 MPa, representing a 10.4% enhancement compared with the untreated sample.更多还原