Effect of Ni content on microwave absorbing properties of MnAl powder

• The grain size and cell volume of Al8Mn5 alloy phase were decreased with the increasing of Ni.
• ε″ and μ″ of powder moves toward low frequency region at the beginning then moves high.
• The minimum reflectivity of (Al8Mn5)0.95Ni0.05 powder was −40.8 dB with 1.8 mm thickness.
• The lowest reflection loss peak of (Al8Mn5)0.95Ni0.05 was −46.3 dB with 2.2 mm thickness.

MnAlNi powder was prepared by the process of vacuum levitation melting and high-energy ball milling, The morphology and phase structure of the powder were analyzed by Scanning Electron Microscope(SEM), X-ray diffraction(XRD) and the effect of the Ni content on microwave absorbing properties of MnAl powder was investigated by an vector network analyzer. The addition of Ni, which improved the microwave absorbing properties of MnAl powder but not changed the composition of Al8Mn5 alloy. The minimum reflectivity of (Al8Mn5)0.95Ni0.05 powder with a coating thickness (d) of 1.8 mm was about −40.8 dB and has better bandwidth effect, the absorbing mechanism of AlMnNi powders on the electromagnetic was related to the electromagnetic loss within the absorbing coatings and the effect of coating thickness on the interference loss of electromagnetic wave.

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