A turbine disk, comprising: a blade disk with a periphery, first and second adjacent disk slots, and a coolant channel extending to the disk periphery; a first blade with a blade platform and blade root disposed within the first disk slot, the blade platform having an inner surface and mateface (32, 34); a second blade with a blade platform and blade root disposed within the second disk slot, the blade platform having an inner surface and a mateface opposing the first blade mateface; a vibration damper comprising an axially-extending main body having an inner surface and opposed damping surface, the main body having a plurality of apertures (122, 124, 126, 128, 130, 132, 134, 136) extending from the inner surface to the opposed damping surface; wherein the damper has a substantially arcuate profile, characterized in that the apertures are slotted apertures, and in that the vibration damper further comprises an edge (108, 110) spanning from the inner surface to the damping surface; and wherein each respective adjacent pair of the slotted apertures each have an elongated shape with a longitudinal axis, wherein the longitudinal axes of each adjacent pair of the slotted apertures are not parallel to each other and the longitudinal axes of each adjacent pair of the slotted apertures intersect at a point off the pressure side edge or suction side edge of the damper main body, the damper being movably captured within a cavity defined by the blade roots, disk periphery, and respective portions of the platform inner surfaces, wherein the coolant channel is in fluid communication with the opposing matefaces via the damper slotted apertures, and wherein the damper slotted apertures are configured and arranged to supply a consistent coolant flow to the opposing matefaces as the damper moves within the cavity. a blade disk with a periphery, first and second adjacent disk slots, and a coolant channel extending to the disk periphery; a first blade with a blade platform and blade root disposed within the first disk slot, the blade platform having an inner surface and mateface (32, 34); a second blade with a blade platform and blade root disposed within the second disk slot, the blade platform having an inner surface and a mateface opposing the first blade mateface; a vibration damper comprising an axially-extending main body having an inner surface and opposed damping surface, the main body having a plurality of apertures (122, 124, 126, 128, 130, 132, 134, 136) extending from the inner surface to the opposed damping surface; wherein the damper has a substantially arcuate profile, characterized in that the apertures are slotted apertures, and in that the vibration damper further comprises an edge (108, 110) spanning from the inner surface to the damping surface; and wherein each respective adjacent pair of the slotted apertures each have an elongated shape with a longitudinal axis, wherein the longitudinal axes of each adjacent pair of the slotted apertures are not parallel to each other and the longitudinal axes of each adjacent pair of the slotted apertures intersect at a point off the pressure side edge or suction side edge of the damper main body, the damper being movably captured within a cavity defined by the blade roots, disk periphery, and respective portions of the platform inner surfaces, wherein the coolant channel is in fluid communication with the opposing matefaces via the damper slotted apertures, and wherein the damper slotted apertures are configured and arranged to supply a consistent coolant flow to the opposing matefaces as the damper moves within the cavity.