Medium temperature internal friction of the Fe-Nb-C alloys

The internal friction in the Fe-Nb-C alloys was measured, It was found that the Snoek peak height (hs) of the alloys held at 700 °C for 1 h and quenched in water is lower, and the more of niobium the alloy contains, the lower the hs is. Unlike general ferro-base materials, the hs of the Fe-Nb-C alloys raises after deforming. For the alloys containing Nb greater than or equal 0.06%(mass fraction), the enlargement of the internal friction in the temperature range of Snoek damping (from room temperature to 150 °C) is obvious, and the high-temperature branch of Snoek peak is evidently raised, or even developed to form a mixing double peak. For the alloys containing Nb greater than or equal 0.33%, the hs is slightly enlarged, so that a Snoek peak and a peak between 80 °C and 130 °C can be observed. There are SKK peaks in all the alloys deformed, while the heights of the SKK peaks(hhSKK) in the alloys containing low niobium are lower. The SKK peaks measured during decreasing temperature all shift toward lower temperature; however, their heights(hhSKK) do not reduce, while the hcSKK in the alloys containing less niobium are all obviously higher than their hhSKK.