Effects Of Ti Addition On Micro Structure And Properties Of Al-Zn Damping Alloy

The development of modern industry puts forward new requirements for damping materials in specific application fields,including lightweight,excellent damping and mechanical properties,and harmless to the environment,etc.Al-Zn damping alloys has attracted wide attention due to its advantages of good damping capacity,low density,low price and good machining properties.However,the mechanical properties of Al-Zn alloys are poor,which limits their wider application to a certain extent.Alloying is one of the important means to improve the comprehensive mechanical properties of alloys,especially the good balance between damping and mechanical properties.In this paper,six Al-Zn based alloys with nominal composition of Al-（50-x）Zn-x Ti-0.1Ce（at.%,x=0,0.1,0.5,1,2,3）were prepared by well type resistance furnace with electromagnetic stirring device.The alloy was rolled at a rolling temperature of 400℃and a reduction of 50%.After rolling,the alloy samples were subjection to and solid solutoin at 380℃for 1-10 h.And the alloy were subjected to and the aged at 150℃for 1-14 h.The microstructure,damping properties and mechanical properties of Al-Zn alloys were studied.The main research contents and results of this article are as follows:For alloys without Ti,the as-cast and rolled Al-Zn damping alloys are mainly composed of a small amount of eutectic andα+ηeutectic structure in black and gray regions.The eutectic structure is composed ofη-Zn matrix andα+ηeutectic distributed on it.After solution and aging treatment at a certain temperature and time,Al-Zn damping alloys are mainly composed of continuousα+ηeutectoid structure.For alloys with Ti,the as-cast and rolled Al-Zn damping alloys are mainly composed of Al₃Ti,eutectic andα+ηeutectic structures in black and gray regions.After solution and aging treatment at a certain temperature and time,the structure of Al-Zn damping alloys are composed of Al₃Ti and continuousα+ηeutectoid structure.With the increase of Ti content,the content of Al₃Ti and eutectic structure increases gradually.For alloys with Ti,the holes and cracks can be observed in the Al₃Ti of the as-cast and rolled alloys.Meanwhile,the holes and cracks can be observed in the matrix of the solution aged alloys.With the extension of solution aging time,the size of Al₃Ti decreases gradually.Theα+ηeutectoid structures in the black and grey areas are lamellar structures.After rolling,the lamellar structure in the black area changes to granular structure,while the lamellar structure remains in the gray area.With the increase of Ti content,the size gradually decreased of the gray eutectoid cell and lamellar and particle structure of the black eutectoid structure.After solution aging,the size ofα+ηeutectoid cells decreases obviously,which have granular and lamellar morphology.With the increase of Ti content,the size of the eutectoid cell and eutectoid structure decreases,but the proportion of lamellar structure increases.With the prolongation of solution and aging time,the coarsening of eutectoid structure occurs,but the proportion of granular structure increases.In general,the damping properties of the alloys increases with the increase of strain amplitude.With the increase of temperature,it first slowly increases and then rapidly increases.Below the critical temperature,it increases slightly with the increase of frequency,while above the critical temperature,it decreases obviously with the increase of frequency.The damping properties of Al-Zn alloys increases first and then decreases with the increase of Ti content,and the damping properties of Al-Zn alloys is the best when Ti content is 0.5at.%.When the strain amplitude is 10^-3,the Q^-1value of the as-cast and rolled 0.5Ti alloy is0.018 and 0.028 respectively.The damping properties of Al-Zn alloys are obviously improved after a certain temperature and time of solution and aging treatment compared with the rolled and cast state.Moreover,with the increase of Ti content and the extension of solution and aging time,the damping properties of the alloys show a trend of first increasing and then decreasing,but the optimal damping properties of the alloys with different Ti content are different in aging time（the optimal aging time of 0Ti,0.5Ti,1Ti and 3Ti is 1,1,4 and 12 h respectively）.When the strain amplitude is 10^-3,the maximum Q^-1values of0.5Ti,1Ti and 3Ti alloys are 0.065,0.062 and 0.064 respectively.Compared with 0Ti alloy(whose Q^-1value is 0.05),the increase is about 30%,24%and 28%respectively.For as-cast Al-Zn damping alloys,the hardness and elongation increase first and then decrease with the increase of Ti content,but the tensile strength has little change.The mechanical properties of Al-Zn alloys are improved to a certain extent,and the hardness,elongation and tensile strength of Al-Zn alloys increase first and then decrease with the increase of Ti content(when Ti content is 1 at.%,the hardness,elongation and tensile strength of Al-Zn alloy are 90.4 HB,24%and 311 MPa respectively.Compared with 0Ti alloy,they increased by 11.9%,140%and 13.1%respectively.After solution and aging treatment at a certain temperature and time,the mechanical properties of the without Ti alloys are improved to a certain extent（the maximum elongation is 345 MPa,the maximum elongation is 34%,which is about 10.9%and 41.7%higher than that of the rolled alloy）,but the mechanical properties of the with Ti alloys are decreased.Moreover,with the extension of solution and aging time,the tensile strength of the ti-free alloy gradually decreases,while the tensile strength of the with Ti alloy gradually increases,and the elongation shows no obvious change rule.