Laser fatigue enhancement method for metallic glass

Abstract

The invention relates to the technical field of metallic glass surface treatment, in particular to a laser fatigue enhancement method for metallic glass. The laser fatigue enhancement method for the metallic glass comprises the main steps as follows: 1) a metallic glass surface is ground and polished, and is cleaned with alcohol; 2) the metallic glass surface is subjected to heat treatment by adopting a CO2 continuous laser, and the treatment temperature is controlled through adjusting the laser process parameters so as to enable the surface to have an amorphous-nanocrystal composite structure; 3) aluminum foil is attached to the heat-treated metallic glass surface; and 4) flowing water is defined as a constrained layer, and an Nd: Glass nanosecond pulse laser is adopted to impact the metallic glass surface to which the aluminum foil is attached, so as to obtain surface enhancement modified metallic glass. The invention integrates advantages of the laser thermal effect, comprehensively regulates and controls the microstructure and the stress state of the metallic glass surface, and effectively enhances the fatigue performance. The invention has a simple process, is suitable for producing the metallic glass on a large scale, and can prepare the metallic glass with a high anti-fatigue performance.

Description

technical field [0001] The invention relates to the technical field of metallic glass surface treatment, in particular to a laser fatigue strengthening method for metallic glass. Background technique [0002] Metallic glass is an amorphous metal alloy with long-range disorder and short-range order of atoms; at present, the research and development of metallic glasses include Zr-based, Cu-based, Mg-based, Pb-based, Al-based, Fe-based, etc. It has many excellent physical and chemical properties, and is a structural or functional material with wide application prospects; as a structural material, metallic glass has high strength, high hardness, high elastic strain limit, high wear resistance and corrosion resistance, etc., but relatively The low fatigue resistance severely limits its engineering applications. [0003] In order to improve the fatigue resistance of metallic glasses, people have been looking for ways to improve their fatigue resistance; introducing a second phase...

AI Technical Summary

Problems solved by technology

[0002] Metallic glass is an amorphous metal alloy with long-range disorder and short-range order of atoms; at present, the research and development of metallic glasses include Zr-based, Cu-based, Mg-based, Pb-based, Al-based, Fe-based, etc. It has many excellent physical and chemical properties, and is a structural or functional material with wide application prospects; as a structural material, metallic glass has high strength, high hardness, high elastic strain limit, high wear resistance and corrosion resistance, etc., but relatively Low fatigue resistance severely limits its engineering applications

[0003] In order to improve the fatigue resistance of metallic glasses, people have been looking for ways to improve their fatigue resistance; introducing a second phase into metallic glasses was initially considered as a potentially effective way to improve fatigue resistance, but studies have found that the second phase Introducing or improving or reducing its fatigue resistance, the results vary. Recently, Launey et al. pointed out that the scale of the second phase significantly affects the fatigue resistance of metallic glasses. When the microscopic length scale of the second phase matches the mechanical crack length scale, The anti-fatigue performance has been significantly improved; in addition, imitating the method of improving the fatigue performance of crystalline materials, people have introduced the method of shot peening into metallic glass in order to obtain the same effect, but the research found that shot peening cannot significantly improve the fatigue of metallic glass performance, which is mainly due to the plastic flow softening near the surface caused by deformation. However, at a depth of 100 μm, the hardness reaches a maximum value, and deformation hardening occurs. Shot peening increases the free volume while increasing the residual compressive stress on the surface. Quantity, and the impact of residual compressive stress and free volume on the fatigue properties of metallic glasses is competing with each other, which is one of the reasons why shot peening cannot effectively improve the fatigue properties of metallic glasses; recent studies have found that the surface plastic deformation strain rate has an The fatigue performance of glass also has an important influence. Metallic glass is in a metastable state, and its structure is easy to change from a high-energy amorphous state to a low-energy crystalline state during deformation, thereby precipitating nanocrystalline phases, which can be used as strengthening phases Restricting the expansion and proliferation of shear bands will cause strain hardening, which will effectively overcome the strain softening phenomenon of metallic glasses and improve their fatigue resistance; in general, there are still many deficiencies in the existing anti-fatigue methods, which make the fatigue resistance of metallic glasses The performance cannot be effectively improved, restricting its engineering application

[0004] In view of the above problems, the present invention proposes a new method of laser fatigue strengthening from the regulation of the surface microstructure and stress state, and uses the dual effects of laser heat and force to comprehensively adjust the microstructure and stress state of the metallic glass surface, so that the residual stress on the surface , the amount of free volume and crystal phase characteristics achieve the best match, effectively strengthen its anti-fatigue performance, avoid the shortcomings of the single effect of existing strengthening methods, and expand the application of metallic glasses