A modular airfoil assembly comprising: a platform member having first and second sides (240, 242) and a hole extending therethrough; an airfoil portion having a shoulder region and a stem (20, 120, 232) extending outward from the shoulder region along an axis and through the hole of the platform member, with the shoulder region abutting the first side of the platform member, the stem having a proximal portion extending away from and adjoining the shoulder region, and a distal end region extending away from the shoulder region and beyond the proximal portion, the proximal portion positioned in the hole and the distal end region including a recessed portion (18, 118, 252), the proximal portion including a first peripheral surface region along which the proximal portion extends from the hole, the recessed portion including a second peripheral surface region (18a, 18b, 118a, 118b, 264) positioned inward toward the axis relative to the first peripheral surface region; a ring element (10, 100) positioned in and extending outward from the second peripheral surface, in a radial direction from the axis, beyond the first peripheral surface, to provide a locking mechanism by which the shoulder region is secured against the first side of the platform member, the ring element comprising first and second members (10a, 10b, 100a, 100b) joined together, the first member comprising first and second mating surfaces (26i, 126i, 128i) and the second member comprising third and fourth mating surfaces (26j, 126j, 128j), a portion of the third mating surface of the second member extending between and bonded to portions of the first mating surface of the first member, and a portion of the fourth mating surface of the second member extending between and bonded to portions of the second mating surface of the first member, wherein the first and second members of the ring element are sintered into a unified structure along the mating surfaces. a platform member having first and second sides (240, 242) and a hole extending therethrough; an airfoil portion having a shoulder region and a stem (20, 120, 232) extending outward from the shoulder region along an axis and through the hole of the platform member, with the shoulder region abutting the first side of the platform member, the stem having a proximal portion extending away from and adjoining the shoulder region, and a distal end region extending away from the shoulder region and beyond the proximal portion, the proximal portion positioned in the hole and the distal end region including a recessed portion (18, 118, 252), the proximal portion including a first peripheral surface region along which the proximal portion extends from the hole, the recessed portion including a second peripheral surface region (18a, 18b, 118a, 118b, 264) positioned inward toward the axis relative to the first peripheral surface region; a ring element (10, 100) positioned in and extending outward from the second peripheral surface, in a radial direction from the axis, beyond the first peripheral surface, to provide a locking mechanism by which the shoulder region is secured against the first side of the platform member, the ring element comprising first and second members (10a, 10b, 100a, 100b) joined together, the first member comprising first and second mating surfaces (26i, 126i, 128i) and the second member comprising third and fourth mating surfaces (26j, 126j, 128j), a portion of the third mating surface of the second member extending between and bonded to portions of the first mating surface of the first member, and a portion of the fourth mating surface of the second member extending between and bonded to portions of the second mating surface of the first member, wherein the first and second members of the ring element are sintered into a unified structure along the mating surfaces.