Fused filament fabrication method using filaments that include a binder configured to release a secondary material

A method comprising:

• fused filament fabricating a fused filament fabricated component by at least:
• delivering a softened first filament to a first set of selected locations at or adjacent to a build surface, and
• delivering a softened second filament to a second set of selected locations at or adjacent to the build surface, wherein the softened first filament comprises a binder and a metal or alloy powder, wherein the binder is configured to release at least one of a secondary material or an alloying element upon heating at or above a conversion temperature, wherein the softened second filament comprises a sacrificial binder and the metal or the alloy powder, the sacrificial binder being different from the binder of the first filament, wherein the first set of locations where the softened first filament is delivered include locations at or near a surface of the fused filament fabricated component, and wherein the second set of locations where the softened second filament is delivered include locations within a bulk volume of the fused filament fabricated component such that the delivered softened first filament is located between the surface of the fused filament fabricated component and the softened second filament within the bulk volume of the fused filament fabricated component;
• removing substantially all of the sacrificial binder of the delivered second filament from the fused filament fabricated component;
• and
• heating the fused filament fabricated component to a temperature at or above the conversion temperature to sinter the metal or the alloy powder to form a sintered part and cause the binder to release the at least one of the secondary material or the alloying element within the sintered part, wherein the release of the secondary material or the alloying element with the heating is configured such that the sintered metal or the sintered alloy powder is case hardened at the locations at or near the surface of the sintered part but not the second set of locations within the bulk volume to increase a wear resistance of the sintered part at the locations at or near the surface.