Study Of Cast Magnesium And Cast Aluminum's Internal Friction

Internal friction is a very effective and sensitive method to detect and study various alloys and metal materials.In the case that the internal structure of the sample is not destroyed,this method can react the changes of materials' grain and crystal boundary.The method can also react the microstructure changes of dislocations and other defects.The purpose of this subject is to lean the internal friction of cast magnesium and cast aluminum.Cast magnesium and cast aluminum including their alloys are the most commonly used metal materials in the industrial production.The changes of these materials' damping properties are closely related to their organizational structure changes.The measurement of internal friction is sensitive to the internal and microcosmic changes.The measurement is also very sensitive to explore the influencing factors.Because of the different research we make some preparation of the relevant materials.The relevant work is the basic research for the future.The relevant work like welding,rolling and composite to the cast magnesium and cast aluminum.The materials we research in this subject include high purity magnesium and high purity aluminum friction samples.We use the audio frequency internal friction instrument which named PJ-? to detect the internal friction curve of materials'different regions.We also detect the internal friction curve of those samples after deformation and heat treatment.We use other measurements such as metal lographic analysis,XRD and determination of chemical components to supplement and verify our results.Experimental results show that the three different parts of the cast magnesium and cast aluminum samples have different internal friction curves.Their internal friction curves are also closely related to the internal friction parameters changes.The internal friction changes with the materials' grain size and grain boundary arrangement.Cast magnesium's surface part has the maximum internal friction.And the columnar zone of cast aluminum which is about 1 cm away from the surface area has the maximum internal friction.By the range of temperature measurement from 270 K to 605 K we find that cast magnesium alloy's friction curve but the cast aluminum sample without treatment has two peaks.After deformation treatment we find that cast magnesium's internal friction curve have only two internal friction peaks.If we make some deformation treatment for the cast magnesium sample we will find that it's internal friction peak at the temperature about 400 K has some changes.This internal friction peak's height and width increases significantly.After the deformation and heat treatment we find that the peaks at low temperature and medium temperature are weakened and disappeared.If the sample is only given the heat treatment not given deformation treatment,it's internal friction curve will not change obviously.But the curve of background internal friction will change.After the aging treatment for the cast magnesium material,we find that it's friction parameters changes in the wake of aging time.