Study On Fatigue Properties Of SiC_p/Al-Si Composite Under Thermo Mechanical Coupling

Al-Si composites reinforced by spray-deposited SiC particles and their matrix materials possess many merits such as high specific strength,great stiffness,good abrasive resistance etc.They are widely used in aerospace,automobile and other industrial fields.Practically,the structural components are often subjected to the high-temperature cyclic loads and fatigue failure is very common to see.The researches on fatigue properties of spray-deposited SiCp/Al-Si composites under the coupling of thermo-mechanical are extremely limited,which restrict their industrial application.Therefore,the study of the fatigue properties of spray-deposited SiCp/Al-Si composites under the coupling of thermo-mechanical is of great significance to industrial application of composite material.In this paper,the author studies the fatigue properties of spray-deposited SiCp/Al-Si composites with different sizes of SiC particles and different contents of matrix Si under the coupling of thermo-mechanical.(1)The fatigue studies of spray-deposited SiCp/Al-7Si composites with different SiC particle sizes at 150? and 300 ? show that the SiCp/Al-Si composites are cyclic softening,and the softening effect becomes increasely obvious with the rise of temperature.At the same temperature,the cyclic softening degree rises with the increasing strain amplitude;For 4.5?mSiCp/Al-7Si and 20?mSiCp/Al-7Si composites,at the low strain amplitude(0.2%-0.25%),the cyclic softening degree of composites have little to do with the particle sizes.However,at high strain amplitude(0.3%),the cyclic softening degree of the large particle reinforced composites increases.In addition,the fatigue life of the composites declines with the increase of the particle size.The author matches Manson-Coffin equation with the plastic strain-fatigue life for SiC particle reinforced Al-7Si composites with different sizes and their matrix alloys at 150? and 300? and finds that the absolute value of fatigue ductility coefficient and fatigue ductility index in smaller SiC composites is larger at the same temperature.(2)The fatigue studies of spray-deposited 4.5?mSiCp particle reinforced Al-7Si composites,Al-13Si composites and Al-20Si composites(7,13,and 20 represent the mass fraction of Si content respectively)at 150? and 300? show that SiCp/Al-Si composites withdifferent Si contents have cyclic softening effect.When the temperature is 150?,different Si contents have no effect on the cyclic softening of the composites at low strain amplitude(0.2%,0.25%);however,at the high strain amplitude(0.3%),the cyclic softening degree of composites increases with the amount of Si content.When the temperature is 300?,the increase of Si content is in line with the improvement of softening degree of the composites and the reduction of their fatigue lives.(3)The study on spray-deposited SiCp/Al-Si composites under the coupling of thermo-mechanical shows that SiCp/Al-Si composites with different sizes of SiC particles and different contents of matrix Si have cyclic softening performance.For different sizes of SiC particles reinforced Al-7Si composites,the degree of cyclic softening decreases with the increase of particle size.However,the cyclic softening of SiCp/Al-Si composites with different Si content does not show obvious regularity.