Amplitude dependent damping measurements in plastically deformed we43 magnesium alloy

O.A. LAMBRI; W. RIEHEMANN; E.J. LUCIONI; R.E. BOLMARO

SAntiago de Chile

Congreso; SAM/CONAMET 2006; 2006

Among commercial magnesium alloys WE 43 (Mg - 4 wt.% Y – 3.4 wt.% Nd – 0.7 wt.% Zr) has probably the best mechanical properties at high temperatures and also exhibits good corrosion resistance. The cost of Yttrium restricts its application to the aerospace industry and other specific applications as in motor racing and helicopters. A study of the precipitation process in WE43 at temperatures higher than 620 K was recently reported. During thermal cycling performed under a heating rate of 1 K/min and a cooling rate of about 14 K/min the elastic modulus was increased. The samples for the present investigation were obtained from WE43 magnesium alloy cast bars, provided by Magnesium Electron (Manchester, UK). The homogenisation treatment was performed under argon atmosphere at normal pressure, at 823 K during 1 hour followed by quenching in water. After the homogenisation treatment the samples were aged at 643 K, under argon atmosphere, for developing the precipitates mentioned. Subsequently the samples were deformed by bending (1, 3 and 5%) at room temperature, in order to explore the effects of the plastic deformation on the precipitation process. Mechanical spectroscopy measurements involving amplitude variations were carried out employing an inverted torsion pendulum. The changes of the damping curves as a function of the strain amplitude of the mechanical oscillations are related to the morphology and volume fraction of the precipitates determined by X-rays diffraction. In addition, electrical resistivity studies were also performed.