Microstructure and Properties of Crack-Free Ti-Modified 6063 Aluminum Alloy TPMS Porous Structures Fabricated by LPBF

Area of Science:

• Materials Science
• Additive Manufacturing
• Metallurgy

Background:

• 6063 aluminum alloy offers good thermal conductivity and strength, suitable for aerospace and thermal management.
• Hot cracking during laser powder bed fusion (LPBF) hinders the manufacturing of complex 6063 aluminum alloy components.
• Developing crack-free aluminum alloys for additive manufacturing is crucial for advanced applications.

Purpose of the Study:

• To investigate the effect of TiH2 nanoparticles on suppressing solidification cracking in 6063 aluminum alloy during LPBF.
• To fabricate Diamond-type porous structures using modified 6063 aluminum alloy via LPBF.
• To evaluate the mechanical properties and thermal conductivity of the fabricated structures.

Main Methods:

• Modification of 6063 aluminum alloy powder with 1.0–4.5 wt.% TiH2 nanoparticles.
• Fabrication of Diamond-type porous structures using triply periodic minimal surfaces (TPMS) via LPBF.
• Characterization of microstructure, mechanical properties (plateau stress, energy absorption), and thermal conductivity.

Main Results:

• Introduction of TiH2 nanoparticles significantly suppressed solidification cracking in the 6063 aluminum alloy.
• In situ formation of Al3Ti particles from TiH2 decomposition provided heterogeneous nucleation sites, reducing grain size by 97.5% (from 30.46 μm to 0.75 μm) and inducing a columnar-to-equiaxed transition.
• The 3.0 wt.% TiH2 addition group demonstrated excellent plateau stress (28.5 MPa) and energy absorption, attributed to fine-grain and Orowan strengthening.
• Thermal conductivity reached 123 W/(m·K) at 100 °C, improved by crack healing and reconstructed heat conduction paths.

Conclusions:

• TiH2 nanoparticle addition is an effective strategy to mitigate hot cracking in 6063 aluminum alloy during LPBF.
• The modified alloy exhibits enhanced mechanical properties and thermal conductivity, suitable for demanding applications.
• This approach provides a pathway for manufacturing high-performance, crack-free, multi-functional aluminum alloy components via additive manufacturing.