High strength, flowable, selectively degradable composite material and articles made thereby

A selectively degradable article, comprising:

• a low density, selectively degradable composite material, the composite material comprising a compacted powder mixture of a first powder, the first powder comprising first metal particles comprising Mg, Al, Mn, or Zn, or an alloy of any of the above, or a combination of any of the above, having a first particle oxidation potential, a second powder, the second powder comprising low-density, hollow or porous ceramic, cermet, intermetallic, metal, or polymer second particles, and a third metal powder, the third metal powder comprising third metal particles having an oxidation potential that is different than the first particle oxidation potential, the compacted powder mixture having a microstructure comprising:
• a matrix comprising the first metal particles;
• and
• the second particles and third particles dispersed within the matrix, the third particles comprising a network of third particles extending throughout the matrix, the low density, selectively degradable composite material having a density of about 3.5 g/cm3 or less;
• wherein the composite material comprises about 15 wt. % to about 50 wt. % of the first metal particles, about 50 wt. % to 85 wt. % of the second particles, and about 0.5 wt. % to about 10 wt. % of the third metal particles, each based on a weight of the composite material.

A selectively degradable article, comprising:

• a lightweight, selectively degradable composite material comprising a first matrix of a first metal comprising Mg, Al, Mn, or Zn, or an alloy of any of the above, or a combination of any of the above, having a first oxidation potential, a second powder, the second powder comprising low-density ceramic, glass, cermet, intermetallic, metal, polymer, or inorganic compound second particles, and a third metal powder, the third metal powder comprising third metal particles having an oxidation potential that is different than the first oxidation potential, the composite material having a microstructure comprising:
• the matrix of the first metal;
• and
• the second particles and third particles dispersed within the matrix, the third particles comprising a network of third particles extending throughout the matrix, the lightweight, selectively degradable composite material having a density of about 3.5 g/cm3 or less.