The addition of Ca into Mg-(3-9)wt%Al alloys increased the hardness at
the high temperatures up to 350 degrees C. In particular, this was re
markable when the mass ratio of Ca to Al was higher than 0.8, probably
owing to the precipitation of the Mg,Ca phase in the alloys. Such all
oys with the Ca/Al mass ratio higher than 0.8 showed excellent heat re
sistance at a moderate temperature. Therefore, they were considered to
be the new promising light-weight heat-resistant alloys for interior
automotive applications.