A memory array comprising strings of memory cells comprises a conductor tier. The conductor tier comprises upper conductor material directly above and directly against lower conductor material of different composition from that of the upper conductor material. The channel-material strings directly electrically couple to the upper and lower conductor materials of the conductor tier. A through-array-via (TAV) region is included and comprises TAVs. The TAVs individually comprise the upper conductor material, the lower conductor material, and a conducting material that is directly below the conductor tier. The lower conductor material is directly against the upper conductor material and directly against the conducting material. The lower conductor material comprises a metal-rich refractory metal nitride directly above and directly against a non-metal-rich refractory metal nitride that is directly against the conducting material. The lower conductor material may also comprise a first elemental-form metal directly above and directly against a second elemental-form metal that is directly against the conducting material Methods are also disclosed.