An Investigation on the Effect of Mn on the Castability of Hypoeutectic Al-2Ni-xMn Alloys

Document Type : Original Research Article

Authors

1 M.Sc., Department of Metallurgy and Materials Engineering, Imam Khomeini International University, Qazvin, Iran.‎

2 Assistant Professor, Department of Metallurgy and Materials Engineering, Imam Khomeini International University, Qazvin, IRAN

3 Professor, Department of Metallurgy and Materials Engineering, Imam Khomeini International University, Qazvin, IRAN

10.22034/frj.2018.112623.1017

Abstract

The effect of Mn addition (2 and 4 wt%) on the microstructure and castability of hypoeutectic Al-2Ni alloy was investigated. According to the results, Mn promotes the formation of Mn(Ni)-rich intermetallics in the microstructure. In the case of Al-2Ni-2Mn alloy the intermetallic compounds are interdendritic type whilst in Al-2Ni-4Mn alloy in addition to interdendritic intermetallics, the large and primary Mn-rich compounds with platelets, polyhedral and dendritic morphologies are present. The fluidity results show that the addition of 2 and 4 wt% Mn enhances the mushy solidification of Al-2Ni alloy leading to a fluidity reduction of 7 and 30%, respectively. Based on the microstructural observations and thermal analysis results, this reduction can be attributed to the formation of primary Mn-rich compounds in the molten alloy. Manganese addition, also, exerts negative impact on the hot tearing resistance of Al-2Ni alloy. The hot tearing susceptibility index (HTS) of Al-2Ni-4Mn alloy is 5 and 12 times higher when compared to those of Al-2Ni-2Mn and Al-2Ni alloys, respectively. SEM investigation of hot teared microcracks and the presence of free dendrites and primary Mn-rich compounds on the fractured surfaces imply on the critical role of primary compounds on the formation of hot tear microcracks.

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References

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Founding Research Journal
Volume 1, Issue 2 - Serial Number 2
December 2017
Pages 69-78

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History

  • Receive Date: 31 December 2017
  • Revise Date: 22 January 2018
  • Accept Date: 30 January 2018

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