A lightweight shape-memory alloy with superior temperature-fluctuation resistance.

Area of Science:

• Materials Science
• Metallurgy
• Aerospace Engineering

Background:

• Advanced applications require materials with a balance of lightness, functionality, and thermal resistance.
• Shape-memory alloys (SMAs) offer strength and strain recovery but face challenges in low-mass and cryogenic performance.
• Existing SMAs struggle to meet the stringent demands of aerospace and extreme environments.

Purpose of the Study:

• To introduce a novel shape-memory alloy designed for advanced applications.
• To address the limitations of current SMAs in terms of mass and cryogenic functionality.
• To characterize the properties and performance of a new Ti-Al-Cr alloy.

Main Methods:

• Chemical composition analysis of Ti75.25Al20Cr4.75.
• Density and specific strength measurements at room temperature.
• Superelasticity testing across a temperature range from 4.2 K to above room temperature.

Main Results:

• The new alloy exhibits low density (4.36 × 10^3 kg m^-3) and high specific strength (185 × 10^3 Pa m^3 per kg).
• Achieved recoverable strain exceeding 7% due to reversible stress-induced phase transformation.
• Demonstrated persistent superelasticity from 4.2 K to above room temperature, with an inverse correlation between transformation stress and temperature below a threshold.

Conclusions:

• The developed Ti-Al-Cr shape-memory alloy meets stringent criteria for aerospace and extreme environments.
• Its unique temperature-dependent transformation behavior and broad operational range are key advantages.
• Potential applications include everyday appliances and components for deep space and cryogenic systems.