Long Term Creep Properties of a Die-Cast Mg-Al-Ca Alloy

摘要

Creep rupture tests were performed for a die-cast Mg-Al-Ca alloy AX52 (X representing calcium) at 29 kinds of creep conditions in the temperature range between 423 and 498 K. The creep curve for the alloy is characterized by a minimum in the creep rate followed by an accelerating stage. The minimum creep rate (ε m) and the creep rupture life (t_(rup)) follow the phenomenological Monkman-Grant relationship; t_(rup) = C_0 / ε m~m. It is found for the AX52 die-cast alloy that the exponent m is unity and the constant C_0 is 2.0 × 10~(-2) , independent of creep testing temperature. The values of m and C_0 are compared with those for another die-cast magnesium alloys. The value m=1 is generally detected for die-cast magnesium alloys. On the contrary, the value of C_0 sensitively depends on alloy composition, which is reduced with increasing the concentration of alloying elements such as Al, Zn and Ca.