Different Content Of Ce 2519 A Aluminum Alloy Under High Strain Rate Of Mechanical Properties And Microstructure

As a new generation of armored material, the key problem of aluminum alloy2519A is to improve the impact property. Aluminum alloy2519A with different contents of Ce (0,0.2%,0.4%) was dynamically impacted by split Hopkinson pressure bar (SHPB) at different temperatures of293K and573K and nominal strain rates of1200s-1,3100s-1and5100s-1. Corresponding true stress-strain curve of each condition was obtained. And the kinetic energy-absorbing capacity and the adiabatic temperature were calculated and analyzed. The hardness of the impacted specimens was tested by Vickers hardness-testing device. The microstructure was investigated by optical microscopy (OM), scanning electron microcopy(SEM), X-ray diffractometer (XRD) and transmission electron microscopy(TEM). Main conclusions are listed in the following:(1)The relationship between strain rates and hardness was established. With increasing strain rate, the hardness of the impacted specimens increased slightly and then decreased. The hardness of alloy with0.2%Ce was higher than that of the alloys with0%Ce and0.4%Ce. Besides, the hardness of specimens impacted at temperature of573K was lower than the counterpart at293K, mainly due to the effect of hot softening.(2)The law of dynamic mechanical property with different alloys at different conditions was obtained. After the analysis of different true stress-strain curves, the0.2%Ce alloy had the highest dynamic yield strength and the highest energy absorption ability compared with others at the same strain rate and temperature, so the dynamic mechanical property of0.2%Ce alloy was the highest. However, the property of the alloy decreased when the addition of Ce reached0.4%. the dynamic yield strength of0.2%Ce alloy reached614MPa, which was obviously higher than that of alloys with0%Ce (550MPa) and0.4%Ce (545MPa).(3)The influence of Ce on the precipitated phases of aluminum alloy2519A was investigated. In case of strain rate of1200s-1and3100s-1, precipitated phases in0.2%Ce alloy were distributed more dispersedly and homogeneously than others, and had the highest area fraction. As the strain rate increased to5100s-1,θ’phase began to coarsen and transform to0at293K while0’phase changed most slowest in0.2%Ce alloy. However, at573K, a re-dissolution phenomenon of hardening phases took place.(4)The existence form of Ce in aluminum alloy2519A was studied and the mechanism of action was explored. Ce mainly exists in the form of rare earth compound with Al and Cu. This type of compound has a relatively high melting point and is distributed both inside grains and along grain boundaries, which corresponding to improvements in the strength of grain boundaries and thermal resistance of the alloy. The action mechanism of Ce was explored in terms of cluster theory, thermodynamic kinetic.