Study On Superplasticity And Electric-superplasticity Behavior Of1420Al-Li Alloy

Lithium is the lightest metal element in the world, and adding it toAluminum metal to form Aluminum-Lithium alloy as an alloying element.Al-Li alloys have low density, high modulus and excellent performance.Among them, the Lithium content is1.8wt%of1420Al-Li alloy isgenerally considered a high-value applications of aeronautical materials.It is the most lightweight (density2.47g/cm3) alloy and has high strengthand stiffness ratio, good corrosion resistance and rather perfectsuperplasticity, becoming the aerospace industry ’s most widely usedamount of Al-Li alloy.In this paper, constant temperature and strain rate of1420Al-Lialloy specimen was carried out on a LETRY tensile testing equipmentunder conditions of varying temperatures (440oC-500oC) and strain rates(1×10-2s-1-1×10-4s-1). Studied alloys high temperature superplasticrheological behavior and microstructure after superplastic deformationvarying with deformation conditions and Simultaneously adding electricpulse which current density (150A/mm-2、167A/mm-2、192A/mm-2、200A/mm-2、213A/mm-2) and pulse frequency (100HZ、150HZ、200HZ、250HZ) during superplastic tensile process on condition temperature480oC,strain rate3×10-4s-1to study the effect of electric pulse on the1420Al-Li alloy superplastic rheological behavior and microstructures.Because mechanical properties of1420Al-Li alloy superplasticdeformation is very sensitive to temperature and strain rate, it isconvenient to get the best superplastic deformation temperature and strainrate. Furthermore, based on the tensile data analysis, establishingconstitutive relation model including temperature and strain rate andanalyzing the variation law of microstructure grains, cavities anddislocations to study its superplastic deformation mechanism and fracturemechanisms. Finally, according to comparison tensile tests between conventional superplasticity and electric-superplasticity, determinedapplying pulse current density and pulse frequency which maximized theability of superplastic deformation and established the analysis of themicroscopic mechanism of electroluminescence superplastic.