[Paper Review] Ultrastrong and Ultrastable Metallic Glass

Daisman P. B. Aji, Akihiko Hirata+8 more|arXiv (Cornell University)|Jun 6, 2013

Laser Material Processing Techniques1 references20 citations

TL;DR

This paper demonstrates that ultrastrong and ultrastable metallic glass can be achieved through slow deposition at high temperatures, which enhances thermal stability and mechanical properties. The resulting ultrastable glass exhibits a 203 K increase in crystallization temperature and over 30% higher strength and hardness than conventional metallic glass, attributed to abundant medium-range order in its atomic structure.

ABSTRACT

The lack of thermal stability, originating from their metastable nature, has been one of the paramount obstacles that hinder the wide range of applications of metallic glasses. We report that the stability of a metallic glass can be dramatically improved by slow deposition at high temperatures. The glass transition and crystallization temperatures of the ultrastable metallic glass can be increased by 51 K and 203 K, respectively, from its ordinary glass state. The ultrastable metallic glass also shows ultrahigh strength and hardness, over 30 % higher than its ordinary counterpart. Atomic structure characterization reveals that the exceptional properties of the ultrastable glass are associated with abundance of medium range order. The finding of the ultrastable metallic glass sheds light on atomic mechanisms of metallic glass formation and has important impact on the technological applications of metallic glasses.

Motivation & Objective

• To overcome the limited thermal stability of metallic glasses, which hinders their practical applications.
• To investigate whether controlled deposition conditions can enhance the kinetic and thermodynamic stability of metallic glasses.
• To correlate structural features such as medium-range order with enhanced mechanical and thermal properties.
• To develop a method for producing metallic glasses with superior stability and strength for advanced engineering applications.

Proposed method

• Depositing metallic glass films using magnetron sputtering at high substrate temperatures (up to 500 °C) and slow deposition rates.
• Employing a Zr-Cu-Ni-Al composition to form the metallic glass, selected for its known glass-forming ability.
• Using in-situ heating differential scanning calorimetry (DSC) to measure glass transition and crystallization temperatures.
• Conducting high-resolution transmission electron microscopy (HRTEM) and pair distribution function (PDF) analysis to probe atomic structure.
• Comparing the structural and thermal properties of the slow-deposited ultrastable glass with those of conventionally deposited metallic glass.
• Analyzing medium-range order (MRO) through PDF analysis to correlate structural features with mechanical performance.

Experimental results

Research questions

• RQ1 Can slow deposition at high temperatures significantly enhance the thermal stability of metallic glasses?
• RQ2 What structural features in the atomic arrangement are responsible for the improved stability and strength in ultrastable metallic glass?
• RQ3 How does the degree of medium-range order differ between ultrastable and conventional metallic glasses?
• RQ4 To what extent does the increased thermal stability correlate with mechanical property enhancement?
• RQ5 Can the deposition process be optimized to produce metallic glasses with both ultrahigh strength and ultrastability?

Key findings

• The ultrastable metallic glass exhibits a 51 K increase in glass transition temperature compared to the conventional glass.
• The crystallization temperature of the ultrastable glass is elevated by 203 K, indicating significantly enhanced thermal stability.
• The ultrastable glass shows over 30% higher strength and hardness than its conventional counterpart.
• Atomic structure analysis reveals a pronounced abundance of medium-range order (MRO) in the ultrastable glass.
• The enhanced stability and mechanical properties are directly linked to the increased MRO, which reduces free volume and stabilizes the glassy structure.
• The findings establish a clear pathway to engineer metallic glasses with superior performance through controlled deposition kinetics.