Increasing Ti–6Al–4V brazed joint strength equal to the base metal by Ti and Zr amorphous filler alloys

Abstract

Microstructural features developed along with mechanical properties in furnace brazingof Ti-6Al-4V alloy using STEMET 1228 (Ti-26.8Zr-13Ni-13.9Cu, wt.%) and STEMET 1406 (Zr-9.7Ti-12.4Ni-11.2Cu, wt.%) amorphous filler alloys. Brazing temperatures employed were 900-950°C for the titanium-based filler and 900-990°C for the zirconium-based filler alloys, respectively. The brazing time durations were 600, 1200 and 1800 s. The brazed joints were evaluated by ultrasonic test, and their microstructures and phase constitutions analyzed by metallography, scanning electron microscopy and X-ray diffraction analysis. Since microstructural evolution across the furnace brazed joints primarily depends on their alloying elements such as Cu, Ni and Zr along the joint. Accordingly, existence of Zr 2 Cu, Ti 2 Cu and (Ti, Zr) 2 Ni intermetallic compounds was identified in the brazed joints. The chemical composition of segregation region in the center of brazed joints was identical to virgin filler alloy content which greatly deteriorated the shear strength of the joints. Adequate brazing time (1800 s) and/ or temperature (950°C for Ti-based and 990°C for Zr-based) resulted in an acicular Widmanstätten microstructure throughout the entire joint section due to eutectoid reaction. This microstructure increased the shear strength of the brazed joints up to the Ti-6Al-4V tensile strength level. Consequently, Ti-6Al-4V can be furnace brazed by Ti and Zr base foils produced excellent joint strengths.

Effects of brazing parameters on the microstructure and tensile shear force of copper sheets using amorphous filler metal

“…5(a). The formation of the dimples implies plastic deformation in the micro-regions, which is sometimes taken as a positive indication of enhancement of the mechanical properties of the joint, According to these results, the improvement of the Cu/Cu-Ni-Sn-P/Cu brazed joint was achieved because the formation of ductile dimple fracture resulted from the strong bonding and fatigue resistance, and when the brittle fracture formation occurred on the brazing joints, the cracks preferred to propagate at the brittle intermetallic compounds, resulting in an easy propagation of the cracks, which leads to a decrease in the strength and fatigue life of the joints [17]. Fig.…”

Low‐Temperature Brazing of Titanium Using Al‐Based Filler Alloys

“…According to the main alloying elements, filler alloys for brazing titanium and its alloys can mainly be classified into five groups: titanium-based [1,14,16,[18][19][20][21], zirconiumbased [16,19,22,23], silver-based [24][25][26][27], aluminum-based [28][29][30][31], and nickel-based [19,32] filler alloys. Attempts of brazing titanium using Al-based filler alloys and other filler systems started over than 60 years ago [33].…”

“…e diffusion of some brazing processes, usually in high temperature, may proceed for a relatively long holding time until achieving the microstructure homogenization over all the joint, which is particularly known as diffusion brazing. Matsu et al, Ganjeh et al and Chang et al [16,17,42] investigated the diffusion brazing of several Ti-and Zr-based fillers, which led to specific microstructures and high shear strengths (Table 1). ese processes involve isothermal solidification and homogenization of the joint [43].…”

Mechanical Properties of Ti-alloy Joint with Ti₂₀Zr₂₀Cu_60-xNi_x(x = 10, 20, 30, 40 and 50) Filler Metal

“…There were first report of high glass forming ability (GFA) of Cu-Ti based alloys namely, Cu 47 Ti 34 Zr 11 Ni 8 and Cu 47 Ti 33 Zr 11 Ni 8 Si 1, which can be cast fully amorphous in the rod forms of 4 and 7 mm in diameter [1][2][3][4][5]. Afterwards, much effort were made in order to develop novel Cu-Ti based bulk glassy alloys possessing more GFA and improved mechanical properties [6,7]. However, it has been observed that the metallic glasses have drawbacks which are the lack of ductility shown in tensile experiments and limited plasticity under macroscopic compression.…”