Preparation of Ti-6Al-4V/AlSi10Mg Bimetallic Materials Using LPBF and MIG Welding

Literature Overview

Published in Hot Working Technology (2026, Vol. 55, No. 7, pp. 148–156), this study by Zhongbei University researchers compares two approaches for fabricating Ti-6Al-4V/AlSi10Mg bimetallic materials: laser powder bed fusion (LPBF) additive manufacturing and MIG welding. The research addresses the growing demand for bimetallic components that combine the high specific strength of titanium alloys with the lightweight, corrosion-resistant properties of aluminum alloys. Funded by Shanxi Provincial patent transformation and overseas returnee research programs, the study provides a direct comparison of interface characteristics and mechanical performance between these two fabrication routes.

Core Technical Findings

The LPBF process produces a liquid-liquid bonded interface influenced by local melting of the titanium substrate, resulting in non-uniform interface morphology and microstructure distribution. In contrast, the MIG welding process creates a solid-liquid bonded interface that is relatively flat and uniform. The interface grain sizes differ significantly: LPBF specimens show average grain sizes of 7.2–9.5 μm at the interface, substantially smaller than MIG specimens. Mechanically, LPBF specimens achieve tensile strength of 170 MPa and elongation of 2.56%, outperforming MIG specimens at 160 MPa and 0.94% elongation. However, the aluminum-side microhardness of LPBF specimens is lower than MIG specimens.

Technical Interpretation of Interface Formation Mechanisms

The fundamental difference between liquid-liquid and solid-liquid bonding at the Ti/Al interface has profound implications for joint integrity. In the LPBF process, the high energy density laser melts both the titanium substrate surface and the deposited aluminum powder simultaneously, creating a true metallurgical liquid-liquid bond. However, this dual melting leads to intermetallic compound formation (such as TiAl3 and TiAl2) that can be brittle and non-uniformly distributed. The local melting of titanium also creates compositional gradients at the interface that affect mechanical properties.

In the MIG welding process, the titanium substrate remains largely solid while the aluminum wire melts and wets the titanium surface, creating a solid-liquid bond. This lower heat input approach produces a more controlled interface with less intermetallic formation, resulting in a flatter, more uniform interface. The reduced intermetallic thickness in MIG specimens may explain the lower elongation despite the more uniform interface, as the interface strength is lower than the fully melted LPBF interface.

Mechanical Performance Analysis

The superior elongation of LPBF specimens (2.56% vs. 0.94%) is particularly significant for fatigue performance in structural applications. Higher elongation indicates greater ductility and energy absorption capacity before fracture, which directly relates to resistance to fatigue crack initiation and propagation. The finer grain structure at the LPBF interface (7.2–9.5 μm) contributes to this improved ductility through the Hall-Petch relationship, where smaller grains provide more grain boundary area for crack deflection and blunting.

The lower aluminum-side hardness in LPBF specimens may be attributed to the different thermal cycling history. LPBF involves rapid heating and cooling with limited time for precipitation hardening in the AlSi10Mg alloy, while MIG welding provides longer residence times at elevated temperatures that promote precipitation strengthening. This trade-off between interface strength and bulk material properties is a critical consideration for component design.

Connection to Engineering Practice

Ti/Al bimetallic components are of significant interest for aerospace applications where weight reduction is paramount. Titanium provides structural integrity while aluminum reduces overall component mass. The LPBF approach offers the advantage of near-net-shape manufacturing with complex geometries, while MIG welding is more established for large-scale production. The choice between these methods depends on the specific application requirements: LPBF for complex, high-performance components where ductility is critical, and MIG for simpler geometries where production volume and cost are primary concerns.

From a quality control perspective, the interface characterization methods described in this study (metallographic examination, hardness profiling, tensile testing) provide a framework for quality assurance of bimetallic joints. The interface grain size measurement and bonding type identification should be incorporated into acceptance criteria for bimetallic component manufacturing.

Study Insights and Implications

This comparative study provides engineers with a clear understanding of the trade-offs between LPBF and MIG fabrication of Ti/Al bimetallic materials. The finding that LPBF produces finer interface grains and superior ductility, while MIG produces a more uniform interface with higher aluminum-side hardness, enables informed process selection based on application requirements. The study highlights that bimetallic joint design must consider not only interface strength but also the mechanical property gradients across the joint, which affect fatigue performance and service life. For aerospace manufacturers developing lightweight structural components, this research provides essential data for process selection and quality specification development.