Abstract:
The good specific strength and specific modulus
of magnesium alloys had drawn the attention of the automotive manufacturers for use in fuel efficient vehicles. Among
the cast magnesium alloys, AZ91 (Mg–9Al–1Zn) is the most
sought alloy because of its good casting properties. However,
this alloy loses its strength and creep resistance properties
above 120 C due to softening of thebphase (Mg17Al12).
Hence, this alloy cannot be used for making heavier engine
components (power train), which require the thermal stability
up to about 250 C. The paper discusses the approach of
modifying the AZ91 alloy by minor alloying additions to
improve the high temperature withstanding capability without
significantly affecting its casting properties. Additions of Ca
to AZ91 alloy to the levels of about 0.4 wt% increased the
ambient and high temperature strength of the base alloy.
Additions of other minor alloying elements such as Sb, Pb,
rare earths etc. can also increase the high temperature capability of the AZ91 by further modifying thebphase structure.
The paper overviews the work carried out by the authors on the
role of different alloying additions on the microstructure and
mechanical properties of AZ91 magnesium alloys
