| Mg alloys(AZ91) were manufactured by sand-casting and gravity-casting method, and Al alloys(ADC12) by die-casting for the application of automotive engine parts. Internal friction of each alloy was measured using the sonic resonance system by free decay method as a function of frequency and temperature. To compare with the measured internal friction value of Mg(AZ91), Al(ADC12) alloys produced in this study, we obtained die cast Mg alloys(AZ91) manufactured by Toyota, Daihatsu and GM, and Al alloys(ADC10) by Toyota. For Mg alloys, specimens produced by die casting showed higher value in internal friction than ones by sand-casting and gravity-casting, mainly due to the difference in grain size. Mg alloys produced by die-casting showed higher internal friction than Al alloys produced by the same method. Internal friction values measured at 393K for Mg alloys(AZ91) increased with increasing frequency. |
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