A method of fabricating a turbine nozzle or a compressor diffuser for a turbine engine, the method comprising: a) making a plurality of single-airfoil vane units, each vane having inner and outer platforms and an airfoil extending between the platforms and connected thereto, and being made by: • forming a fiber blank by three-dimensional weaving, the blank being in the form of a strip and comprising a first segment with second and third segments extending the first segment at respective first and second longitudinal ends thereof, each of the second and third segments (104, 106) being split into two portions (104a, 105a; 106a, 107a) on either side of a zone of non-interlinking (101a; 101b) extending within the thickness and across the entire width of the strip; • forming a fiber preform for the vane to be made by laterally deploying the two portions (104a, 105a) of the second segment and the two portions (106a, 107a) of the third segment and shaping said portions so as to obtain inner and outer platform preforms (114a, 116a), and by shaping the first segment so as to obtain an airfoil preform; and • at least partially densifying the fiber preform with a matrix in order to obtain and at least partially densified vane with inner an outer platforms incorporated therein; and b) assembling and bonding together a plurality of at least partially densified vanes: • the bonding being performed by a process comprising at least one step selected from: a step of bonding by brazing and a step of bonding by co-densification; and • the inner or outer platform of a first vane (112 2) comprising an inner or outer passage-constituting platform portion that is bonded to an inner or outer platform portion of an adjacent second vane in a bonding zone extending over at least a portion of the inside surface of the inner passage-constituting platform portion of the first vane (112 2) and/or over at least a portion of inner surface of the outer passage-constituting platform portion of the first vane (112 2). a) making a plurality of single-airfoil vane units, each vane having inner and outer platforms and an airfoil extending between the platforms and connected thereto, and being made by: • forming a fiber blank by three-dimensional weaving, the blank being in the form of a strip and comprising a first segment with second and third segments extending the first segment at respective first and second longitudinal ends thereof, each of the second and third segments (104, 106) being split into two portions (104a, 105a; 106a, 107a) on either side of a zone of non-interlinking (101a; 101b) extending within the thickness and across the entire width of the strip; • forming a fiber preform for the vane to be made by laterally deploying the two portions (104a, 105a) of the second segment and the two portions (106a, 107a) of the third segment and shaping said portions so as to obtain inner and outer platform preforms (114a, 116a), and by shaping the first segment so as to obtain an airfoil preform; and • at least partially densifying the fiber preform with a matrix in order to obtain and at least partially densified vane with inner an outer platforms incorporated therein; and • forming a fiber blank by three-dimensional weaving, the blank being in the form of a strip and comprising a first segment with second and third segments extending the first segment at respective first and second longitudinal ends thereof, each of the second and third segments (104, 106) being split into two portions (104a, 105a; 106a, 107a) on either side of a zone of non-interlinking (101a; 101b) extending within the thickness and across the entire width of the strip; • forming a fiber preform for the vane to be made by laterally deploying the two portions (104a, 105a) of the second segment and the two portions (106a, 107a) of the third segment and shaping said portions so as to obtain inner and outer platform preforms (114a, 116a), and by shaping the first segment so as to obtain an airfoil preform; and • at least partially densifying the fiber preform with a matrix in order to obtain and at least partially densified vane with inner an outer platforms incorporated therein; and b) assembling and bonding together a plurality of at least partially densified vanes: • the bonding being performed by a process comprising at least one step selected from: a step of bonding by brazing and a step of bonding by co-densification; and • the inner or outer platform of a first vane (112 2) comprising an inner or outer passage-constituting platform portion that is bonded to an inner or outer platform portion of an adjacent second vane in a bonding zone extending over at least a portion of the inside surface of the inner passage-constituting platform portion of the first vane (112 2) and/or over at least a portion of inner surface of the outer passage-constituting platform portion of the first vane (112 2). • the bonding being performed by a process comprising at least one step selected from: a step of bonding by brazing and a step of bonding by co-densification; and • the inner or outer platform of a first vane (112 2) comprising an inner or outer passage-constituting platform portion that is bonded to an inner or outer platform portion of an adjacent second vane in a bonding zone extending over at least a portion of the inside surface of the inner passage-constituting platform portion of the first vane (112 2) and/or over at least a portion of inner surface of the outer passage-constituting platform portion of the first vane (112 2).