MamookhoElizabeth Makhatha

Bio: MamookhoElizabeth Makhatha is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 10 citations.

Influence of Rapid Solidification on the Thermophysical and Fatigue Properties of Laser Additive Manufactured Ti-6Al-4V Alloy

Abstract: Modern industrial applications require materials with special surface properties such as high hardness, wear and corrosion resistance. The performance of material surface under wear and corrosion environments cannot be fulfilled by the conventional surface modifications and coatings. Therefore, different industrial sectors need an alternative technique for enhanced surface properties. The purpose of this is to change or enhance inherent properties of the materials to create new products or improve on existing ones. The most effective and economical engineering solution to prevent or minimize such surface region of a component is done by fiber lasers. Additive manufacturing (AM) is a breaking edge fabrication technique with the possibility of changing the perception of design and manufacturing as a whole. It is well suitable for the building and repairing applications in the aerospace industry which usually requires high level of accuracy and customization of parts which usually employ materials known to pose difficulties in fabrication such as titanium alloys. The current development focus of AM is to produce complex shaped functional metallic components, including metals, alloys and metal matrix composites (MMCs), to meet demanding requirements from aerospace, defense, and automotive industries.

Experimental investigation of laser metal deposited icosahedral Al-Cu-Fe coatings on grade five titanium alloy

Abstract: Laser Additive Manufacturing is relatively new in the manufacturing industry. This paper focuses on the effect of hybrid coatings of Al-Cu-Fe on a grade five titanium alloy (Ti6Al4V) using laser metal deposition (LMD) process at different laser power and scanning speeds. Icosahedral Al-Cu-Fe as quasicrystals are a relatively new class of materials which exhibit unusual atomic structure and useful physical and chemical properties. Ti6Al4V/Al-Cu-Fe composite were analysed using Optical microscopy, Scanning electron microscopy (SEM) with energy dispersive microscopy (EDS), indentation testing, X-Ray Diffraction (XRD), corrosion and wear testing. deposit width and height, heat affected zone (HAZ) height), dilution rate, aspect ratio and powder efficiency of each sample remarkably increased with increasing laser power due to the laser-material interaction. It was observed that there are higher number of aluminium and titanium presented in the formation of the composite. The indentation testing reveals that for both scanning speed of 0.8m/min and 1m/min, the mean hardness value decreases with increasing laser power. It was found that due to dilution effect, a part of Ti entered into molten pool from the substrate. The results indicate that Ti, Al 3 Ti, Ti 3 Al, CuTi 2 can be produced through the in situ metallurgical reactions during the LMD process.

Review on direct metal laser deposition manufacturing technology for the Ti-6Al-4V alloy

Abstract: Copyright: 2020 Springer. Due to copyright restrictions, the attached PDF file only contains the abstract of the full text item. For access to the full text item, please consult the publisher's website: https://doi.org/10.1007/s00170-019-04851-3 A free fulltext non-print version of the article can be viewed at https://rdcu.be/b747a

Numerical investigation of laser deposited Al-based coatings on Ti-6Al-4V alloy

Abstract: Titanium Alloy (Ti6Al4V) opened a wide range of useful applications in aerospace industries; these industries make use of different additive manufacturing (AM) techniques to obtain parts of different properties for different uses by this titanium alloy. Ttitanium alloy mainly stands out due to the properties such as high specific strength to weight ratio, and excellent corrosion resistance. Despite these benefits, the formation of defects such as pores and cracks play a vital role in the quality of the deposited coatings. The presence of these unwanted artefacts on laser deposited coatings depends on the melting, cooling and solidification of the melt pool. In this research, a simulation of the heat transfers and fluid dynamics of the melt pool is developed to predict the process parameters and reinforcement proportions on the clad geometry quality. The results were compared to the experimental results for confirmation and validation. Numerical modelling using COMSOL multiphysics 5.2 revealed the thermal behaviour of the coated samples.

Effects of Fe addition on the microstructure and corrosion properties of quasicrystalline Al-Cu-Fe coatings

Abstract: The performance of material surface under wear and corrosion environments cannot be fulfilled by the conventional surface modifications and coatings. Therefore, different industrial sectors need an alternative technique for enhanced surface properties. Titanium and its alloys possess poor tribological properties which limit their use in certain industries. This paper focuses on the effect of hybrid coatings Al-Cu-Fe on a grade five titanium alloy using laser metal deposition (LMD) process. Icosahedral Al-Cu-Fe as quasicrystals are a relatively new class of materials which exhibit unusual atomic structure and useful physical and chemical properties. A 3kW continuous wave ytterbium laser system (YLS) attached to a KUKA robot which controls the movement of the cladding process was utilized for the fabrication of the coatings. The titanium cladded surfaces were investigated for its microstructure and corrosion properties at different laser processing conditions. The samples were cut to corrosion coupons and immersed into 3.5% NaCl solution at 28oC using Linear Polarization (LP) techniques. The cross-sectional view of the samples was analysed. It was found that the geometrical properties of the deposits such as width, height and the Heat Affected Zone (HAZ) of each sample remarkably increased with increasing laser power due to the laser-material interaction. It was observed that there are higher number of aluminium and titanium presented in the formation of the composite. The cladded layer showed a uniform crack free surface due to optimized laser process parameters which led to the refinement of the coatings. Sample Al-Cu-5Fe showed increase of 1538.3-times the polarization resistance of the substrate (Ti-6Al-4V alloy). Large amount of aluminium and less amount of iron favour the chemical performance of composite thereby increasing the polarization resistance.