Abstract

Amorphous metals which are synonymously called metallic glasses form a rather young group of engineering materials. Compared to crystalline metals they offer unique combinations of properties: tensile strength, hardness, elastic strain, resistance against corrosion and abrasive wear are rather high. In order to minimize crystal growth, rapid solidification from the liquid phase is required. High cooling rates are a characteristic property of the additive manufacturing technology Laser Beam Melting in Powder Bed (LBM). This paper shows first results of processing Ti50Cu32Ni15Sn3 by LBM. Unlike many other alloys with high glass forming ability, it does not contain costly rare earth elements. No literature is known to the authors about LBM of this material. Because relative density close to 100 % is a prerequisite for producing parts with high mechanical performance, a parameter study was conducted varying scan speed, hatch distance and laser power in wide ranges. The obtained samples are characterized by metallographic sections, hardness measurements and X-ray diffraction. Apart from reaching high relative densities, a wide variation in Vickers hardness over the length of samples was found. It corresponds to the locally different thermodynamic conditions. Apart from introducing a new material with promising properties to the manufacturing technology of LBM, this might open up a new approach to modify mechanical material properties in a single work piece made from uniform powder by adapting LBM process parameters. Both the range of applications for LBM as well as the range of geometries producible from amorphous metals might be expanded.

Highlights

  • The development of metallic glass goes back to 1960 when P

  • Each time the laser focus passes through the pyrometer spot, it causes a sharp peak in the radiation temperature

  • By conducting parameter studies for processing Ti50Cu32Ni15Sn3 powder in Laser Beam Melting (LBM), it is proven that cuboid samples with 5 mm edge length can be built with relative density close to 100 %

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Summary

INTRODUCTION

The development of metallic glass goes back to 1960 when P. Numerous alloys have been researched for their glass forming abilities, usually being composed of three or more chemical elements. Amorphous metals based on Zirconium have already been commercialized. Such alloying components are either costly on their own (e.g. Pd) or because of their strong chemical attraction to Oxygen (e.g. Zr) which requires special precautions for processing. All suffer from severe restrictions to create complex geometries as well as provide sufficient cooling rates for large parts. In this context, dimensions over 1 mm are considered large. "m: Glass forming ability criterion Tx: Onset crystallisation temperature Tg: Glass transition temperature Tl: Liquidus temperature Rc: Critical cooling rate. Et al have recently published experimental results from LBM of an iron-based amorphous metal, yet with the main focus on showing the feasibility in principle [8]

MATERIALS AND METHODS
LBM Processing
Analysis
Powder Characterization
Thin Walls
Hardness Measurement
Pyrometer Analysis
CONCLUSION AND OUTLOOK
Full Text
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