Damping behavior of ZA27alloys doped with silicon

The ZA27 alloy doped with silicon possesses excellent wear-resistant properties,but the damping capacity of the alloy(i.e.Q-1) has not been studiedin detail.Inthis paper,the damping behaviors and relative dynamic modulus of the as-cast ZA27alloy and ZA27 alloys doped with 4wt %Si(hereinafter ZA27-4 %Si alloy) were investigated using a multifunctional internal fric-tion apparatus and thus the damping mechanisms of the two alloys were analyzed.It was found that damping capacities of the twoalloys increase with the increasing of temperature and decreasing of frequency,while it is independent of vibration amplitude.The damping capacities of the ZA27 alloy and ZA27-4 %Si alloy are relatively high;the values ofQ-1in ambient temperature are6.87×10-3and 5.83×10-3respectively at a strain frequency of 1.0 Hz.The relative dynamic modulus of the two alloys increa-ses when the vibrating frequencyincreases,and the modulus decreases as temperatures increases in ZA27 alloy.For ZA27-4 %Sialloy,the modulus is independent of temperature lower than 100℃;Above 100℃,it decreases slightly with the increasing oftemperature.It can be concluded that the slipping of phase interfaces or the viscous sliding of grain boundary,dislocation’s os-cillation,the infinitesi mal plastic deformation that was caused by the difference of elastic module and heat expansion coefficientbetween phases of the alloy yielded the damping of the alloys.Based onthe experi ment results,it is proposed that ZA27-4 %Si isan excellent alloy with the properties of high damping,high strength,good wear-resistance,and proper for the sliding bearingalloys.