Selective Laser Melting Additive Manufacturing Of Fe-based Metal Glass And Its Composites

Amorphous alloy is a high-performance metal material developed in the middle of the last century.Due to its short-range ordered and long-range disordered atomic structure,it has a series of excellent properties,such as high strength,high hardness,corrosion resistance and soft magnetic properties.However,it has been difficult to achieve breakthrough progress in the preparation of large-size bulk amorphous alloy samples,which has greatly restricted the application of amorphous alloys in other fields.Although some scholars have achieved the preparation of large-size bulk amorphous alloys by selective laser melting additive manufacturing technology in recent years,the problems of cracks and poor surface morphology are common in samples,especially in the Fe-based amorphous alloy selection Laser melting forming research.In addition,due to the thermal influence of the heat of the laser beam on the solidified amorphous structure in the vicinity of the molten pool,it is difficult to completely suppress the crystallization phenomenon in the shaped sample.Therefore,the selective laser melting additive manufacturing technology is difficult to prepare the ideal shaped sample of the fully amorphous alloy component.In this paper,(Fe_0.76B_0.1Si_0.09P_0.05)₉₉Nb₁ was used as the base material to study the law of sample quality changing with forming parameters and Tungsten Carbide?WC?particles on the quality,micro characteristics and amorphous properties of the sample.The specific research work of this paper is as follows:?1?The planetary ball mill,high-speed mixing mixer,and V-roller mixer were used to prepare the WC-reinforced amorphous alloy composite powder,and the influence of different mixing principles on the morphology and uniformity of the powder was analyzed.Experiments show that the V-shaped roller mixer has little effect on the morphology of the powder,and can achieve uniform mixing of WC and amorphous alloy powder,while maintaining good powder flowability.?2?Fe-based amorphous alloy samples were prepared with different forming parameters,and the influence of laser energy density on the micro-morphology,defects,and properties of the samples was analyzed.Experiments show that the metal powder has a small amount of melting and a high viscosity when the linear energy density value is less than 0.200,and dense large-sized pore defects are formed inside the formed sample;When the linear energy density value is higher than 0.280,there is a severe gradient thermal stress between the melt channels,which leads to the formation of huge crack defects in the samples;When the laser energy density value is in the median,the sample has fewer cracks and pore defects,and has a higher density.At the same time,as the Fe-based amorphous alloy powder has been partially crystallized,severe crystallization is generally present in the shaped samples.?3?Preparation of near-spherical WC and spherical WC-reinforced Fe-based amorphous alloy composite samples,and analyze the effects of WC particles on the quality,surface morphology,and amorphous properties of the samples.Experiments show that WC particles can significantly affect the heat transfer efficiency and cause the morphology of the sample melt channel to change.The near-spherical WC powder with a smaller particle size can uniformly block the conduction of heat,and partially dissolve and disperse in the matrix,effectively suppressing the long-range diffusion crystallization of the matrix element.Due to the large volume of spherical WC,the difference in its distribution density results in a very uneven blocking effect on heat conduction,resulting in severe distortion of the melt profile.In addition,crack defects in WC-reinforced Fe-based amorphous alloy composite samples are more sensitive to changes in laser energy density.Under higher energy density conditions,the melt viscosity decreases,the melting amount of WC particles increases,the bonding strength of the matrix and WC particles is improved,and crack propagation is effectively suppressed.