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| Effect of Zr on microstructure and mechanical properties of sintered Al-5Si
aluminum alloy for automobile body |
| WU Zhiguang1，ZHOU Jianmin2，ZHANG Fangdong1 |
| 1Department of Mechanical Engineering，Shanxi Institute of Mechanical and Electrical Engineering，
Changzhi 046011，China；2China North Industries Group Huaihai Industry Group Co.，Ltd.，Changzhi
046011，China |
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Abstract The comprehensive properties of sintered Al-5Si aluminum alloy used for mobile body were improved
by adding Zr element. The microstructure and slow strain rate tensile（SSRT）test were used to analyze the microstructure
and mechanical properties. The results show that Zr can inhibit the recrystallization process and reduce
the recrystallization grain size. More black second-phase particles are formed in Al-5Si-Zr plate，and the recrystallized
grains increases obviously. The second phase structure of dispersion distribution is found in all the plates，
which has obvious needle structure，and the number decreases after Zr is added.Zr can nail the quenching vacancy
of Al-5Si-Zr plate，form less movable vacancy，make it difficult for the grain boundary phase to nucleate. The tensile
strength and elongation of the plate in NaCl solution are lower than that in the air.After the addition of Zr，the
tensile strength of the plate in air decreases from 346 MPa to 321.5 MPa，and the elongation decreases from 12.2%
to 11.41%. At the fracture site of Al-5Si-Zr plate，a dense distribution of dimples is formed，resulting in transgranular
ductile fracture，and the fracture size and depth are reduced.
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Received: 16 January 2020
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2021, Vol. 31 
