Study On The Mechanical Properties And Strengthening Mechanism Of Rare Earth Elements Yb And La Reinforced ZL201 Allo

Since the beginning of the 21 st century,with the rapid development of science and technology,the automotive industry has ushered in unprecedented prosperity,and lightweight is the mainstream of the current industry.As a material with excellent comprehensive properties,aluminum alloy has received extensive attention and applications.ZL201 alloy has excellent heat resistance and strength,but the casting and corrosion resistance are poor,and it is prone to defects such as shrinkage,shrinkage holes and cracking.Studies have shown that rare earth elements can improve the grain structure and comprehensive properties of aluminum alloys.Therefore,this paper takes ZL201 alloy as the research object to study the effects of Yb and La in the lanthanide element on their microstructure and mechanical properties.The effects of T5(530°C×8h+540°C×8h+175°C×4h,water quenching temperature 80°C)and T5′(530°C×4h+540°C×8h+175°C×4h,water quenching temperature 80°C)on the microstructure and mechanical properties of the alloy were discussed.Further determine the optimal amount of rare earth elements to add.The results of the study are as follows:(1)In the casting state,with the increase of Yb and La elements,the grains of ZL201 alloy are continuously refined,and the mechanical properties of the material gradually increase to the limit value and then decrease,showing a parabolic change law.When the amount of Yb added was 0.6wt.%,the tensile strength and microhardness of the alloy were 283.43 MPa and 96 HV,respectively,which were 26.80% and 18.52%higher than when it was not added.When the amount of La was 0.6wt.%,the tensile strength and microhardness of the alloy were 280.91 MPa and 93 HV,respectively,which were 24.84% and 14.84% higher than when they were not added.(2)The solution time of T5 heat treatment is 4 hours longer than that of T5′ heat treatment,and the tensile strength and microhardness of ZL201 alloy after T5 heat treatment are 290.68 MPa and 90 HV,respectively,which are 3.25% and 3.54% higher than T5′ heat treatment.(3)After T5 heat treatment,the mechanical properties of ZL201 alloy with rare earth elements are further improved.When the amount of Yb added was 0.6wt.%,the tensile strength and microhardness of the alloy were 349.55 MPa and 113 HV,respectively,which were 20.25% and 25.56% higher than when not added.When the amount of La added was 0.6wt.%,the tensile strength and microhardness of the alloy were 343.71 MPa and 110 HV,respectively,which were 18.24% and 22.22% higher than when they were not added.It was further determined that the optimal amount of rare earth elements added was 0.6wt.%.(4)The atomic radius of Yb element is less than that of La,and the strengthening effect of Yb element on ZL201 alloy is better than that of La,so the mechanical properties of ZL201 alloy with Yb element are higher than those of La.