nanoparticles adding influence on fatigue behavior of AA5052 and aluminum composite materials

Abstract

Abstract In the present thesis, the influence of nanoparticles zirconia ZrO2, titanium dioxide TiO2 and alumina Al2O3 of the average size (25-35nm) adding with same weight percent 7% to Aluminum metal matrix AA5052 on tensile strength, Vickers hardness and fatigue properties was studied. Stir casting teqnique was used to fabricate the composite materials. The analysis of SEM examination reveals that there is a uniform and good homogeneous dispersion of ZrO2, TiO2 and Al2O3 nanoparticles into the molten AA5052 alloy row matrix. The results of this study showed that the mechanical properties, ultimate tensile stress, yield stress and Vickers hardness of the composites was improved compared to the row matrix AA5052. The composite with 7wt% ZrO2 exhibited higher ultimate tensile stress, yield stress and hardness compared with the other two composites with TiO2 and Al2O3 nanoparticles, the improvement was 54%, 33.8% and 25% percentage for ultimate tensile stress, yield stress and hardness respectively. The study showed that the fatigue strength at 107 cycles under constant loading of the composite with 7wt% ZrO2 exhibited higher than that of row matrix AA5052 as 31%, also the results showed improvement in fatigue life factor FLIF at different stress level 60, 50 and 45MPa as (40.6, 76.7 and 53%) respectively. The improvement in fatigue life (FLIF%) under variable amplitude loading for high-low and low-high sequence loading of AA5052 with 7wt% ZrO2 composite were enhanced by 44% and 37.7% respectively compared with the fatigue life of AA5052 at same amplitude stresses. According to Miner rule the total damage for low-high sequence loading was (1.0101) for the matrix and (0.8825) for composite with ZrO2, but for High-low sequence loading the total damage was 0.808 for matrix and 0.785 for composite with ZrO2 . ii A numerical solution by FEM was done using ANSYS.16.1 workbench to predict fatigue life of the composites. A good agreement in behavior was founded between the experimental work and numerical data. The maximum percentage error of fatigue strength between the experimental and numerical values 4.14% for the matrix and less than for composites.