Methods of forming bonded articles including similar or dissimilar materials and related articles

A method of forming an article comprising:

• forming a first preform exhibiting a density percentage of from about 50% to about 90% of a theoretical maximum sintering density of a first feed material used to form the first preform;
• forming a second preform exhibiting a density percentage of from about 50% to about 90% of a theoretical maximum sintering density of a second feed material used to form the second preform, wherein the density percentage of the first preform is different from the density percentage of the second preform, and wherein the density percentage of the first preform relative to the second preform is based on at least one dimension of the first preform relative to the second preform;
• positioning the first preform directly adjacent to the second preform;
• bonding the first preform to the second preform via a final sintering process to form a bonded article such that the bonded article exhibits no visible interface between the first preform and the second preform using microscopy techniques configured to achieve about a 2000× magnification;
• and
• wherein the first preform is positioned in a hot zone and the second preform is positioned in a cold zone during the bonding step, and wherein a temperature of the hot zone differs from a temperature of the cold zone by at least one percent.