Ｔｉ基ろうによるＴｉ−２１Ｖ−４Ａｌβ型チタン合金の液相拡散接合

Abstract

Diffusion brazeability of β-type Ti alloy (Ti-21V-4Al) using newly developed Ti-20Zr-2OCu-2ONi amorphous filler has been investigatedd by electron microscopy, EDX microanalyses, and tensile tests of the joints. The brazeability was compared with solid state diffusion bondability of the same material, and the effect of aging heat treatments of the joint generally carried out for the alloy was also examined.Results of metallurgical examination of the joints indicated that the liquid layer at the joint interface became to disappear during holding at the joining temperature, and that the joint structure and composition finally became similar to those of the base metal.As for mechanical properties of the joint, even the joint made at 850C for 15 min under the joining pressure of 0.6 MPa, which is fairly lower than that required in solid state diffusion bonding of the same material, was fractured in the base metal with tensile strength of 680 MPa. Furthermore, the joint strength could be increased up to 1400MPa by aging heat treatment after joining.These results demonstrate that the use of developed Ti-base filler metal improves the diffusion weldability, and make it possible to produce the joint equivalent to the base metal even under a fairly low joining pressure.