Single-phase 300 nm thick Bl-NaCl structure polycrystalline Ti1-xWxN alloys, with compositions extending from TiN to Ti0.3W0.7N, have been grown at 500 degrees C on amorphous SiO2 by ultra-high vacuum reactive magnetron sputtering from Ti and W targets in 10 mTorr N-2 discharges. The anion-to-cation ratio ranged from slightly overstoichiometric (1 < N/(Ti + W) less than or equal to 1.1) in TiN-rich alloys to understoichiometric in WN-rich alloys with N/(Ti + W) = 0.9 at x = 0.7. The relaxed alloy lattice constant a(0) initially increased with increasing W and then decreased below the stoichiometric TiN value, a(TiN) = 0.42416 nm, for understoichiometric (i.e. N deficient) alloys with x > 0.5. Plan-view and cross-sectional transmission electron microscopy showed that the films exhibited a columnar microstructure, with typical column diameters of 20-25 nm, and a preferred orientation which changed from strong(111) in TiN-rich alloys to strong (002) in WN-rich alloys. The normalized room-temperature resistivity increased linearly at a rate d rho/rho(TiN)dx = 2.5 with increasing WN concentration x due to a combination of alloy, boundary, and free-surface scattering. All of the above results as a function of film composition are directly related to differences in the intensity of low-energy particle irradiation (primarily backscattered N) during film growth.