Magnesium alloy with adjustable degradation rate

A method of producing a composition comprising a Mg matrix and nanosized precipitates;

• wherein the composition has a Zn content ranging from 0.1 wt. % Zn to 2.0 wt. % Zn;
• a Ca content ranging from 0.2 wt. % Ca to 0.5 wt. % Ca;
• a content of one or more other elements;
• and a remainder content being Mg;
• wherein the nanosized precipitates are less noble or more noble than the Mg matrix, or a mixture thereof, the method comprising the steps of:
• (a) casting a mixture containing (i) magnesium having a purity of at least 99.96 wt. %;
• (ii) from 0.1 wt. % to 2.0 wt. % zinc having a purity of at least 99.9 wt. %;
• and (iii) from 0.2 wt. % to 0.5 wt. % calcium metal having a purity of at least 99.9 wt. %;
• (b) solution heat treating of the cast alloy at two different temperatures wherein a first temperature is below an eutectic temperature of Mg—Zn and a second temperature is above the eutectic temperature of the ternary Mg—Zn—Ca system to thereby form a MgZnCa alloy containing from 0.1 wt. % Zn to 2 wt. % Zn, and a calcium content ranging from 0.2 wt. % to 0.5 wt. %, and having a content of one or more other elements, with the remainder being Mg,
• (c) age heat treating between 100° C. and 300° C. to create dispersed nanosized precipitates prior to extrusion;
• (d) extruding the alloy into a desired shape;
• and
• (e) low temperature annealing of the shaped alloy at about 150° C. to about 250° C.