1. A medical implant comprising:a material composition, the material composition comprising a matrix of coated core particles, wherein each coated core particle comprises a core particle and multiple coating layers disposed about said core particle;
wherein the core particles comprise Mg or an alloy or oxide thereof, or Ca or an alloy or oxide thereof, or Al or an alloy or oxide thereof; and
wherein the multiple coating layers comprise an innermost coating layer comprising a dissolution activator comprising Fe, Mg, C, Cu, or alloys thereof; an outermost coating layer comprising Ti, C, or alloys thereof; and at least one intermediate coating layer positioned between the innermost coating layer and the outermost coating layer, the at least one intermediate coating layer comprising Al, Zn, Al2O3, Ca, Ti, C, Sr, or combinations thereof;
wherein each coating layer exhibits electrical potential relative to an adjacent coating layer of the multiple coating layers; and
wherein the outermost coating layer is biodegradable in a human body at a first dissolution rate, wherein the innermost coating layer is biodegradable in the human body at a second dissolution rate, wherein the at least one intermediate coating layer is biodegradable in the human body at a dissolution third rate, and wherein the first, second and third dissolution rates are different, and wherein the material composition is biodegradable in the human body at a constant or substantially constant dissolution rate.