# DUT researchers reach 360 MPa shear strength in TC4 and 316L joints in the lab

- Published: 2026-11-07 03:25 UTC
- Section: Machines & Making › Materials science
- Tags: vacuum brazing, TC4 titanium alloy, SS316L stainless steel, amorphous filler ribbon, shear strength, intermetallic compounds, Dalian University of Technology
- URL: https://realtech.media/news/rt-6fc3da2f0f86c330c81bd6b4_dut_researchers_reach/

**A melt-spun Ti-Zr-Cu-Ni-Hf amorphous filler enabled high-strength vacuum brazing of titanium alloy to stainless steel by limiting brittle phases.**

![DUT researchers reach 360 MPa shear strength in TC4 and 316L joints in the lab](https://realtech.media/media/2026/11/fe0e52de96c8afdf.jpg)
*Unknown authorUnknown author or not provided, Wikimedia Commons, Public domain*

Researchers from Dalian University of Technology have developed an amorphous ribbon filler doped with hafnium to vacuum-braze Ti-6Al-4V (TC4) titanium alloy directly to SS316L stainless steel, reporting shear strengths up to 360 ± 12 MPa in laboratory tests, according to a study published in China Welding (中国焊接：英文版) [1]. Joining titanium to austenitic stainless steel typically suffers from the formation of brittle intermetallic compounds, specifically TiFe and TiFe₂, which promote premature cracking under mechanical stress.

To control phase growth at the interface, the team synthesized a Ti36.27-Zr12.50-Cu37.48-Ni12.50-Hf1.25 (at.%) amorphous alloy ribbon using melt-spinning [1]. The researchers tested a vacuum brazing parameter matrix spanning temperatures from 910 °C to 950 °C and dwell times between 5 and 40 minutes. The peak shear strength of 360 ± 12 MPa was recorded at 910 °C with a 40-minute hold, while a 10-minute hold at the same temperature yielded 353 ± 9 MPa [1]. Increasing the brazing temperature above 930 °C led to the rapid growth of coarse intermetallic layers, cutting joint shear strength by up to 50% [1].

## Interfacial microstructure and kinetics

Microstructural examination revealed that the brazed seam divides into three distinct zones: an (α + β)-Ti diffusion layer containing fine α-Ti lamellae adjacent to the TC4 base, a central eutectic and intermetallic seam, and an Fe-Cr-rich reaction layer contacting the SS316L interface [1]. The authors reported that hafnium and zirconium remained concentrated within the central seam, suppressing grain coarsening, while mutual diffusion of titanium, copper, and iron formed transitional gradients [1].

Kinetic calculations confirmed that layer growth follows parabolic time dependence and Arrhenius temperature behavior [1]. The activation energy for diffusion was 261 kJ/mol on the TC4 side and 149.6 kJ/mol on the SS316L side, showing that titanium diffusion governs the overall interdiffusion process [1].

## Failure modes and phase effects

Microhardness mapping identified Ti₂Cu and TiFe compounds as the primary strengthening constituents in the joint seam, though their intrinsic brittleness simultaneously acted as the main source of embrittlement [1]. Fractographic analysis demonstrated brittle intermetallic cleavage on the SS316L side, contrasting with a mixed ductile-brittle fracture mode on the TC4 side [1]. The findings define a narrow processing window centered near 910 °C to balance atomic interdiffusion against excessive intermetallic growth in dissimilar titanium-steel assemblies [1].

## Sources

1. [中国焊接：英文版](https://doi.org/10.1016/j.cwe.2026.100034)
2. [EurekAlert](https://www.eurekalert.org/news-releases/1150749)

---

Source: RealTech, realtech.media — https://realtech.media/news/rt-6fc3da2f0f86c330c81bd6b4_dut_researchers_reach/