Structurally complex phase engineering enables hydrogen-tolerant Al alloys.

Area of Science:

• Materials Science
• Metallurgy
• Hydrogen Embrittlement Research

Background:

• Hydrogen embrittlement (HE) limits the durability and application of aluminum (Al) alloys, particularly in hydrogen energy technologies.
• Existing hydrogen trapping sites in Al alloys, such as intermetallic compounds, are often low in density compared to strengthening nanoprecipitates.

Purpose of the Study:

• To engineer a high-density dispersion of dual nanoprecipitates in Sc-added Al-Mg alloys for enhanced hydrogen trapping.
• To improve the hydrogen embrittlement resistance and mechanical strength of aluminum alloys.

Main Methods:

• A size-sieved complex precipitation strategy was employed in Sc-added Al-Mg alloys.
• A two-step heat treatment induced heterogeneous nucleation of Al3(Mg,Sc)2 on Al3Sc nanoprecipitates larger than 10 nm.
• The size-dependent formation mechanism of the core-shell nanostructures was investigated.

Main Results:

• Achieved a high-density dispersion of Al3Sc and core-shell Al3(Mg,Sc)2/Al3Sc nanophases with superior hydrogen-trapping capabilities.
• The tailored dual nanoprecipitate distribution resulted in a 40% increase in strength and a fivefold improvement in HE resistance.
• Demonstrated record tensile uniform elongation in hydrogen-charged Al alloys (up to 7 ppmw H).

Conclusions:

• The developed size-sieved precipitation strategy effectively enhances hydrogen resistance in high-strength Al alloys.
• This approach is adaptable for large-scale industrial production and applicable to various Al-Mg-based alloys.
• The findings offer a promising route for advancing materials for the hydrogen economy.