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Abstract

Inconel 738 LC superalloy is bonded by 5Ni 5Ti 90Al filler alloy by active brazing process. A furnace brazing under a protective argon atmosphere is used for joining samples at 825 °C and constant holding time (15 min.). The relationship amid the mechanical properties and microstructure of the brazed joints has been investigated. Three layers are identified by XRD analyses to pinpoint the reaction phases that form in the joint during the brazing process. The results show: the first layer (the base metal zone), the major phase is Ni(Al, Ti); the second layer (the diffusion zone), the major phases are Al0.5CNi3Ti0.5, AlNi3, and AlTi3. The third layer (bonding zone), the major phases for each sample are Al3Ti, and AlNi2Ti for sample bonded by 5Ni 5Ti 90Al (wt. %) at 825 ºC. The bonding phase width (BPW) concluded from EDS analysis is 40 µm for sample bonded by 5Ni 5Ti 90Al. The microhardness value is 841.7 HV due to intermetallic and centreline eutectic ingredients in the concentrated brazing seam. The bonded phases created by filler metal Ni-Ti-Al produce an intermetallic bonding phase with mechanical properties close to that produced when the base metal is ceramic material.

Keywords

Inconel 738 LC alloys 5Ni 5Ti 90Al brazed joints

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