Effect Of Zn Layer On Interface Of Al-Mg Roll-boding

The Al-Mg composite plate,which possesses the advantages of Mg alloys with low density,high specific strength,good thermal conductivity,excellent damping shock absorbing and impact resistance,and also possesses the advantages of Al alloys with good plasticity and great corrosion resistance ability,is applied widely in areas of aeronautics and astronautics,transportation and 3C,etc.however,during the hot-rolling cladding and diffusion annealing processes,the brittle phase of Al3Mg2 and Al12Mg17 are formed at the interface,which weakens the bond strength of the interface greatly.In this paper,the effects of the thickness of Zn layer,the parameters of rolling and annealing on the morphology,compound and property at the interface are studied by means of metallographic,SEM and EDS analysis,and the following conclusion are drawn:(1)For the hot-rolling cladding process of Al-Mg without Zn layer,when the rolling temperature is 300?,the interface is flat and there are some cracks and not compounds at the interface.When the rolling temperature is higher than 350?,the brittle phases of Al3Mg2 and Al12Mg17 are formed;For the hot-rolling cladding process of Al-Mg with Zn layer,the Zn layer is breaked when the rolling temperature is 250?.when the rolling temperature is 300?,the interface is clear and there are not compounds at the interface,when the rolling temperature is 350?,the MgZn2 is formed near the Mg side at the interface,when the rolling temperature is 400?,the Zn layer with the thickness of 0.02mm is partially melted;when the deformation rate is higher than 50%,the interface is clear and there are not the compounds at the interface,and the uniformity of the deformation distribution between Al and Mg layers increases with the increase of the deformation rate whether the Zn layer is present or not.(2)The interfacial shear strength and the number of bending of the Al-Mg cladding plate without Zn layer increase at first and then descend with the increase of rolling temperature,and increase with the increase of deformation rate;that of the Al-Mg cladding plate with Zn layer increase with the increase of rolling temperature and deformation rate.That of the Al-Mg cladding plate with Zn layer is 50%higher than without Zn layer,moreover,that of the Al-Mg cladding plate with Zn layer thickness of 0.02mm is higher than the thickness of 0.08mm.(3)For the annealing process of Al-Mg cladding plate without Zn layer,there is?-Al3Mg2 near the Al side at the interface and ?-Al12Mg17 near the Mg side at the interface.The thickness of the interfacial compounds increases with the increase of annealing temperature and annealing time,and the thickness of ?-Al3Mg2 is more than that of?-Al12Mg17;For the annealing process of Al-Mg cladding plate without Zn layer,there is AlZn near the Al side at the interface and MgZn2 near the Mg side at the interface when the annealing temperature is 200 and 300?.However,when the annealing temperature rises up to 400?,the Zn layer with the thickness of 0.02mm disappears and ?-Mg21(ZnAl)17,?1-Mg32(ZnAl)48 and ?-Al12Mg17 are formed at the interface;the thickness of MgZn2 and AlZn increases and the Zn layer with the thickness of 0.02mm disappears firstly before that of 0.08mm when the annealing time increases.(4)The interfacial shear strength and the number of bending of the Al-Mg cladding plate increase at first and then descend with the increase of annealing temperature and annealing time whether the Zn layer is present or not;that of the annealed Al-Mg cladding plate with Zn layer is 40%higher than without Zn layer,moreover,that of the annealed Al-Mg cladding plate with Zn layer thickness of 0.08mm is higher than the plate with the thickness of 0.02mm.(5)Adding Zn layer between Al and Mg is a method of restraining effectively the formation of the brittle phase during the production of the Al-Mg cladding plate,whose process parameters:the rolling temperature is 350?,the deformation rate is 70%,the annealing temperature is 300? and the annealing time is 1hour;the interfacial shear strength is 45 MPa and the number of bending is 26 for the Al-Mg cladding plate produced by this process.