A turbine rotor, comprising: a disk rotationally disposed about a central axis, the disk including a rim portion having a first radially outermost rim portion and a second rim portion, the second rim portion disposed radially inward of the first radially outermost rim portion; a plurality of blade posts disposed on and spaced circumferentially about the first radially outermost rim portion,_the plurality of blade posts including a first blade post disposed in the first radially outermost rim portion; and a plurality of tabs disposed on and spaced circumferentially about the second rim portion, the plurality of tabs including a first tab disposed in the second rim portion, the first tab positioned radially inward of the first blade post, wherein the first blade post has a tip, a base, and a forward facing surface comprising a blade post transition portion, wherein the blade post transition portion is disposed at a location between the tip and the base, wherein the first blade post includes a plurality of branches spaced radially between the base and the tip, and wherein the blade post transition portion is disposed proximate the radially most inward branch; wherein the forward facing surface includes a first portion that extends radially inward from the tip to the blade post transition portion; and a slope portion which extends radially inward from the blade post transition portion towards the base, wherein the slope portion extends beyond the base to intersect with a face portion of the first tab, wherein an axial profile of the first tab includes the slope portion and said face portion, the blade post transition portion defining a radius of curvature. a disk rotationally disposed about a central axis, the disk including a rim portion having a first radially outermost rim portion and a second rim portion, the second rim portion disposed radially inward of the first radially outermost rim portion; a plurality of blade posts disposed on and spaced circumferentially about the first radially outermost rim portion,_the plurality of blade posts including a first blade post disposed in the first radially outermost rim portion; and a plurality of tabs disposed on and spaced circumferentially about the second rim portion, the plurality of tabs including a first tab disposed in the second rim portion, the first tab positioned radially inward of the first blade post, wherein the first blade post has a tip, a base, and a forward facing surface comprising a blade post transition portion, wherein the blade post transition portion is disposed at a location between the tip and the base, wherein the first blade post includes a plurality of branches spaced radially between the base and the tip, and wherein the blade post transition portion is disposed proximate the radially most inward branch; wherein the forward facing surface includes a first portion that extends radially inward from the tip to the blade post transition portion; and a slope portion which extends radially inward from the blade post transition portion towards the base, wherein the slope portion extends beyond the base to intersect with a face portion of the first tab, wherein an axial profile of the first tab includes the slope portion and said face portion, the blade post transition portion defining a radius of curvature. a first portion that extends radially inward from the tip to the blade post transition portion; and a slope portion which extends radially inward from the blade post transition portion towards the base, wherein the slope portion extends beyond the base to intersect with a face portion of the first tab, wherein an axial profile of the first tab includes the slope portion and said face portion, the blade post transition portion defining a radius of curvature.