Disclosed are methods for immobilizing hazardous waste within a solid waste form and solid waste forms that can be formed according to the methods. The methods include dispersing waste materials throughout a metallic matrix material to form a particulate mixture followed by solidification of at least the metallic components of the mixture to form a solid waste form. The solidification can be carried out either incrementally in an additive manufacturing process or in bulk, but in either case, the solidification process is carried out such that waste material remains located within the solid metallic matrix essentially as deposited and there is little or no opportunity for the waste materials to separate and disperse throughout the matrix material. As such, the waste is retained within the solidified matrix essentially as deposited with no possibility for the waste to coalesce either during or following the solidification process.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH
 This invention was made with Government support under Contract No. DE-AC09-085R22470 awarded by the United States Department of Energy. The Government has certain rights in the invention.