The Mg-RE alloys are attractive, constructional materials, especially
for aircraft and automotive industry, thanks to combination of low
density, good mechanical properties, also at elevated temperature, and
good castability and machinability. Present paper contains results of
fatigue resistance test carried out on Elektron 21 magnesium alloy,
followed by microstructural and fractographical investigation of
material after test. The as-cast material has been heat treated
according to two different procedures. The fatigue resistance test has
been conducted with 106 cycles of uniaxial, sine wave form stress
between 9 MPa and 90 MPa. Fractures of specimens, which ruptured during
the test, have been investigated with scanning electron microscope. The
microstructure of specimens has been investigated with light microscopy.
Detrimental effect of casting defects, as inclusions and porosity, on
fatigue resistance has been proved. Also the influence of heat
treatment's parameters has been described.