A method of installing a fastener assembly on a substrate having a longitudinally oriented substrate aperture extending through a thickness thereof between proximal and distal substrate surfaces (350, 352), the method comprising: providing a bolt having a shaft and a head, the shaft having proximal and distal shaft ends (108, 110) longitudinally separated by a shaft body, the head being located at the proximal shaft end, and at least a bondable portion of the shaft body spaced from the proximal shaft end being at least partially made of a diffusion bondable material; inserting the distal shaft end of the bolt longitudinally into the substrate aperture from the proximal substrate surface, wherein inserting the distal shaft end of the bolt longitudinally into the substrate aperture from the proximal substrate surface includes applying a longitudinally tensile force to the shaft to reduce a lateral cross-sectional area of the shaft and thereby facilitate the insertion of at least a portion of the shaft through the substrate aperture; extending the distal shaft end of the bolt from the distal substrate surface with at least a portion of the bondable portion of the shaft body being located distal to the distal substrate surface; providing at least one collar having proximal and distal collar ends longitudinally separated by a collar body, the collar body including a longitudinally oriented collar aperture extending through a thickness thereof between proximal and distal collar surfaces (228, 230), the collar aperture defining an inner collar wall having a bondable portion which is at least partially made of a diffusion bondable material; inserting the distal shaft end of the bolt longitudinally into the collar aperture from the proximal collar surface; extending the distal shaft end of the bolt into the collar aperture with the bondable portion of the shaft body being at least partially located lateral to the bondable portion of the inner collar wall; activating the diffusion bondable material of both of the inner collar wall and the shaft body; and bonding the shaft and the collar into an integral fastener assembly structure through activation of the diffusion bondable material. providing a bolt having a shaft and a head, the shaft having proximal and distal shaft ends (108, 110) longitudinally separated by a shaft body, the head being located at the proximal shaft end, and at least a bondable portion of the shaft body spaced from the proximal shaft end being at least partially made of a diffusion bondable material; inserting the distal shaft end of the bolt longitudinally into the substrate aperture from the proximal substrate surface, wherein inserting the distal shaft end of the bolt longitudinally into the substrate aperture from the proximal substrate surface includes applying a longitudinally tensile force to the shaft to reduce a lateral cross-sectional area of the shaft and thereby facilitate the insertion of at least a portion of the shaft through the substrate aperture; extending the distal shaft end of the bolt from the distal substrate surface with at least a portion of the bondable portion of the shaft body being located distal to the distal substrate surface; providing at least one collar having proximal and distal collar ends longitudinally separated by a collar body, the collar body including a longitudinally oriented collar aperture extending through a thickness thereof between proximal and distal collar surfaces (228, 230), the collar aperture defining an inner collar wall having a bondable portion which is at least partially made of a diffusion bondable material; inserting the distal shaft end of the bolt longitudinally into the collar aperture from the proximal collar surface; extending the distal shaft end of the bolt into the collar aperture with the bondable portion of the shaft body being at least partially located lateral to the bondable portion of the inner collar wall; activating the diffusion bondable material of both of the inner collar wall and the shaft body; and bonding the shaft and the collar into an integral fastener assembly structure through activation of the diffusion bondable material.