The Institute of Physics, Chinese Academy of Sciences has made breakthrough progress in wear-resistant amorphous alloy materials!

Tech 2023-07-01 00:34:44 Source: Network

Diamond like materials exhibit excellent friction and wear properties due to their ultra-high hardness and self-lubricating ability.However, due to environmental factors such as humidity, temperature, atmosphere, and size limitations, the application of diamond like materials is limited to coatings and fillers for composite materials

Diamond like materials exhibit excellent friction and wear properties due to their ultra-high hardness and self-lubricating ability.However, due to environmental factors such as humidity, temperature, atmosphere, and size limitations, the application of diamond like materials is limited to coatings and fillers for composite materials. Compared to diamond like materials, metals are more widely used. However, the hardness of metals is often low, lacking self-lubricating ability, and the friction and wear performance of most metal materials is far inferior to that of diamond like materials. Obtaining diamond like friction and wear properties in metal materials will greatly broaden the selection range of wear-resistant materials.

Amorphous alloys retain the disordered atomic structure of liquid melts and have the characteristics of high strength and hardness. Unlike traditional metals, amorphous alloys exhibit liquid like properties on their surfaces, resulting in self-lubricating effects, resulting in many amorphous alloys exhibiting friction coefficients (COFs< 0.2) close to those of diamond like materials.The high strength of amorphous alloys also gives them good wear resistance, with a wear rate Ws of approximately 10-5-10-6mm3/Nm. Although this wear rate is much lower than that of common metal materials, it is still very high compared to the wear rate of diamond like materials, which is about 10-6-10-9mm3/Nm. The key to reduce the wear rate of amorphous alloys is to improve the structural stability and Fracture toughness. Unfortunately, most amorphous alloys are prone to structural relaxation or precipitation of crystalline phases during high-speed reciprocating friction due to low glass transition temperature and crystallization temperature, leading to local cracks and reduced wear resistance. Therefore, finding amorphous alloys with stable structure and good toughness is an important way to improve friction and wear performance.

Liu Yanhui and Wang Weihua from the Institute of Physics, Chinese Academy of Sciences, based on the concept of material genetic engineering, developed high-throughput experimental methods in the early stage, developed high-temperature bulk amorphous alloys, found new criteria for amorphous alloy forming ability, and provided a favorable tool for efficient research and development of new amorphous alloy materials.The above research results are based onAchievingdiamond LikewearinTa richmetalicglassesAdvancedScience

Recently, the team's researchers designed high-throughput characterization methods for the mechanical properties of amorphous alloys (Figure 1), and combined with the previously developed high-throughput preparation and amorphous screening technologies, developed ultra-wear-resistant high-temperature amorphous alloys with friction coefficients and wear rates comparable to diamond like materials.

The team chose the Ir-Ni-Ta high-temperature amorphous alloy system as the breakthrough point. This alloy system has good amorphous formation ability and high glass transition temperature, which can overcome the structural instability problem of amorphous alloys during friction. In addition, the high strength and hardness exhibited by the alloy system also contribute to improving wear resistance. However, the difficulty lies in how to obtain components with good toughness within the alloy system, thereby reducing the possibility of crack formation during friction. The team utilized high-throughput experimental techniques developed in the early stage to prepare composite samples containing a large amount of alloy components, and determined the range of amorphous formation components. Based on the characteristics of shear deformation of amorphous alloys and the correlation between the number of shear bands and the toughness of materials, the team proposed a high-throughput characterization method using Nanoindentation to apply large deformation to induce shear band and crack formation. Combined with indentation morphology characterization, this method can quickly obtain the trend of toughness changes with alloy composition over a large range of components, thereby confirming the composition range with crack resistance and plasticity. In addition, the Nanoindentation itself can also obtain hardness and modulus data at the same time. The team further demonstrated the effectiveness of this high-throughput characterization method through micro/nano mechanical characterization of specific components, and discovered amorphous alloys with extremely low friction coefficient and wear rate in the Ta rich region of Ir Ni Ta composite samples. Micro mechanical testing shows that the compressive strength of the Ta rich amorphous alloy is as high as 5GPa, and the formation of a large number of shear bands indicates that the alloy has good toughness. In addition, thermal stability tests and high-temperature oxidation tests have shown that the Ta rich amorphous alloy also exhibits excellent structural stability (crystallization temperatureTX> 1073K, oxidation temperature> 920K). In a room temperature atmospheric environment, the friction coefficient of the Ta rich amorphous alloy was only 0.05 when tested with diamond ball heads, and only 0.15 when tested with G-Cr alloy ball heads. The most noteworthy aspect is that the wear rate of the Ta rich amorphous alloy is only~10-7mm3/Nm (Figure 2). This friction and wear performance is close to the friction and wear performance of diamond like materials under similar test conditions (Figure 3). These results not only demonstrate the effectiveness of newly developed high-throughput mechanical characterization methods for rapid screening of strengthening and toughening amorphous alloy components, but also contribute to understanding the origin of wear resistance of amorphous alloys.

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