Design And Mechanical Properties Of Multicomponent Light-weight Alloys

Multicomponent alloys break through the limitation of alloying of traditional alloys and initiate new ideas of material design,thus obtaining superior properties than traditional alloys,such as high strength,high hardness,high wear resistance,good corrosion resistance,high temperature oxidation resistance and high temperature softening resistance,etc.The reported light-weight multicomponent high entropy alloys are of utmost potential in the field of aerospace applications because of ultral-high specific strength.However,the research on multi-component light-weight high entropy alloys,which exhibit limited plastic deformation ability,is still not significantly taken seriously.Therefore,it is significant to develop a new multi-component lightweight alloy system.Based on light elements such as Al,Li,Mg,Ca,Si and Y,five kinds of multi-component ultra-light series alloys are designed in this paper by using the design idea of multi-component alloys,and other five kinds of multi-component alloys of light series are designed by adding Sr,Zn and Cu into those elements,analyzing deeply and systematically the influence of the phase composition,phase volume fraction and micro-structure of these two series alloys on strength,plasticity and other mechanical properties.Multi-component ultra-light alloys?Al-Li-Mg-Ca-Si?Y??have ultra-low density?1.46-1.7 g cm-3?,high specific strength(205-327 kPa m³ kg^-1)and relatively low modulus of elasticity?30-55 GPa?,and the alloy Al1_9.9Li₃₀Mg₃₅Si₁₀Ca₅Y_0.1 has especially high fracture strength?710±26 MPa?and yield strength?556±20 MPa?.Al₁₅Li₃₈Mg₄₅Ca_0.5Si_1.5 and Al₁₅Li₃₉Mg₄₅Ca_0.5Si_0.5 alloys exhibiting downright good compressive plasticity were prepared by adjusting their composition,with the compressive plasticity being more than 45%and the strength remaining high.It is found that this alloy has increasingly excellent properties with its composition gradually closing the solid solution phase region,such as,the large volume fraction of the solid solution,the better the compressive plasticity,the lower the elastic modulus and the smaller the density.Five alloys of light series with different compositions theirs density is about 1.72±0.05-2.09±0.05 g cm^-3 and strength usually is higher than 300 MPa,have been prepared.Al ₂₁Li₂₁Mg₃₇Ca₂₁,Al ₁₅Li₃₅Mg₄₀Si₅Zn₅ and Al ₁₅Li₃₅Mg₄₀Si₅Cu₅ have higher specific strength than Ti6Al4V,and the specific strength of Al ₁₅Li₃₅Mg₄₀Si₅Zn₅ and Al₁₅Li₃₅Mg₄₀Si₅Cu₅ are higher than that of Vit BMG.Al₁₅Li₃₅Mg₄₀Si₅Zn₅ alloy has better compressive plasticity?fracture strain about 15%?and extremely high toughness(71.05J m^-3)compared with other four alloys.The results show that the better plasticity of the alloy comes from the larger volume fraction of solid solution,and the strength comes from the reinforcement of intermetallic compounds with high modulus and hardness.