The influence of cooling rate on the damping characteristics of the ZnAl4Cu1 alloy

Abstract

The paper presents the results of damping coefficient tests on the ZnAl4Cu1 alloy (ZL5). The damping coefficient has been calculated on the basis of specimen measurements obtained with the use of the signal echo method. The method consists in passing an ultrasonic wave through the tested material. The ultrasonic wave from a transmitting and receiving head passes through a specimen, bounces off its bottom surface and comes back to the measuring head in the form of a signal echo. The difference in the signal intensity between the first and the second echo in relation to the distance travelled by the ultrasound wave is avalue of the material's damping characteristics. The specimens were cast into three molds made of different materials, i.e. green sand, plaster and metal. The thermophysical properties of these materials are different, affecting the rate of heat absorption from the cast. Three series of specimens have been obtained which have different cooling rates. The specimens were then subjected to ultrasound and microscopic tests to assess the alloy structure. The internal alloy structure affects its damping properties to a great extent.