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1
Content available Characterization of Ceramic Particle Reinforced Titanium Composite Produced Via Powder Metallurgy
Angel D. A., Miko T., Benke M., Gacsi Z.
Archives of Metallurgy and Materials
|
2020
|
Vol. 65, iss. 2
515--519
EN
Nowadays, titanium is one of the most popular materials for aeronautical applications due to its good corrosion resistance, formability and strength. In this paper, rutile reinforced titanium matrix composites were produced via powder metallurgy. The steps included high energy ball milling of raw titanium and rutile powders in a planetary ball mill, which was followed by cold-pressing and sintering without external pressure. For the characterization of the milled powders and the sintered composites, scanning electron microscope, X-ray diffraction and compressive strength examinations were carried out. The results showed that the rutile has a strengthening effect on the titanium matrix. 1 wt% rutile increased the compressive strength compared to the raw titanium. Increasing the milling time of the metal matrix decreased the compressive strength values.
2
Content available Influence of Ceramic Particles on the Microstructure and Mechanical Properties of SAC305 Lead-Free Soldering Material
Kumar Manoj Pal, Gergely G., Koncz-Horvath D., Gacsi Z.
Archives of Metallurgy and Materials
|
2019
|
Vol. 64, iss. 2
603--606
EN
In this study, silicon carbide (SiC) reinforced lead-free solder (SAC305) was prepared by the powder metallurgy method. In this method SAC305 powder and SiC powder were milled, compressed and sintered to prepare composite solder. The composite solders were characterized by optical and scanning electron microscopy for the microstructural investigation and mechanical test. Addition of 1.5 wt.% and 2 wt.% ceramic reinforcement to the composite increased compressive strengths and microhardness up to 38% and 68% compared to those of the monolithic sample. In addition, the ceramic particles caused an up to 55% decrease in the wetting angle between the substrate and the composite solder and porosity was always increased with increase of SiC particles.
3
Content available Whisker-Like Formations in Sn-3.0Ag-Pb Alloys
Koncz-Horváth D., Gergely G., Gacsi Z.
Archives of Metallurgy and Materials
|
2017
|
Vol. 62, iss. 2B
1027--1031
EN
In this study, different types of whisker-like formations of Sn-3.0Ag based alloy were presented. In the experimental process the amount of Pb element was changed between 1000 and 2000 ppm, and the furnace atmosphere and cooling rate were also modified. The novelty of this work was that whisker-like formations in macro scale size were experienced after an exothermic reaction. The whiskers of larger sizes than general provided opportunities to investigate the microstructure and the concentration nearby the whiskers. In addition, the whisker-like formations from Sn-Ag based bulk material did not only consist of pure tin but tin and silver phases. The whisker-like growth appeared in several forms including hillock, spire and nodule shaped formations in accordance with parameters. It was observed that the compound phases were clustered in many cases mainly at hillocks.
4
Content available Investigation of Multicomponent Lead-Free Solders
Gyenes A., Benke M., Teglas N., Nagy E., Gacsi Z.
Archives of Metallurgy and Materials
|
2017
|
Vol. 62, iss. 2B
1071--1074
EN
According to the directives (RoHS and WEEE) adopted by the European Union, lead has been banned from the manufacturing processes because of its health and environmental hazards. Therefore, the development of lead-free solders is one of the most important research areas of the electronic industry. This paper investigates multicomponent Sn-Ag-Cu based lead-free solders with different compositions. The properties of the six-component Innolot (SAC+BiSbNi) and two low-Ag containing alloys were compared with the widespread used SAC307 solder. Microstructure investigations and X-ray diffraction measurements were performed to analyze and identify the formed phases, furthermore, tensile tests and microhardness measurements were executed to determine the mechanical properties of the examined solders.
5
Content available Effect of Wetting Agent and Carbide Volume Fraction on the Wear Response of Aluminum Matrix Composites Reinforced by WC Nanoparticles and Aluminide Particles
Lekatou A., Gkikas N., Karantzalis A. E., Kaptay G., Gacsi Z., Baumli P., Simon A.
Archives of Metallurgy and Materials
|
2017
|
Vol. 62, iss. 2B
1235--1242
EN
Aluminum matrix composites were prepared by adding submicron sized WC particles into a melt of Al 1050 under mechanical stirring, with the scope to determine: (a) the most appropriate salt flux amongst KBF4 , K2 TiF6 , K3 AlF6 and Na3 AlF6 for optimum particle wetting and distribution and (b) the maximum carbide volume fraction (CVF) for optimum response to sliding wear. The nature of the wetting agent notably affected particle incorporation, with K2 TiF6 providing the greatest particle insertion. A uniform aluminide (in-situ) and WC (ex-situ) particle distribution was attained. Two different sliding wear mechanisms were identified for low CVFs (≤1.5%), and high CVFs (2.0%), depending on the extent of particle agglomeration.
6
Content available Development of Crack Detection Method with 2 Dimensionally Generated 3 Dimensionally Reconstructed Images in THT Solder Joints
Gergely G., Koncz-Horváth D., Weltsch Z., Gacsi Z.
Archives of Metallurgy and Materials
|
2017
|
Vol. 62, iss. 2B
1033--1038
EN
This work represents an interesting development in the detection and interpretation of crack evolution in through hole technology (THT) solder joints, which based on the development of general and common method. Serial sectioning is a useful method because it overcomes the problems associated with traditional two-dimensional metallographic techniques by providing information about (micro)structures in three-dimensions. In our work, serials sectioning with reconstruction method was utilized to visualize the 3D nature of cracks in through hole solder joint. Accurate quantitive analysis of the cracks, such as crack length, position and extension are presented with a help of the developed method: newly defined parameter and serial-cross sectioning method.
7
Content available Correlation Between Pin Misalignment and Crack Length in THT Solder Joints
Molnar A., Benke M., Gacsi Z.
Archives of Metallurgy and Materials
|
2017
|
Vol. 62, iss. 2B
1063--1066
EN
In this manuscript, correlations were searched for between pin misalignments relative to PCB bores and crack propagation after cyclic thermal shock tests in THT solder joints produced from lead-free solder alloys. In total, 7 compositions were examined including SAC solders with varying Ag, Cu and Ni contents. The crack propagation was initiated by cyclic thermal shock tests with 40°C / +125°C temperature profiles. Pin misalignments relative to the bores were characterized with three attributes obtained from one section of the examined solder joints. Cracks typically originated at the solder/pin or solder/bore interfaces and propagated within the solder. It was shown that pin misalignments did not have an effect on crack propagation, thus, the solder joints’ lifetime.
8
Content available Whisker Formation On Galvanic Tin Surface Layer
Radanyi A. L., Sycheva A., Gacsi Z.
Archives of Metallurgy and Materials
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2015
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Vol. 60, iss. 2B
1341--1345
EN
The present work reports the effect of substrate composition, thickness of the tin electroplate and its morphology on pressure-induced tin whisker formation. Pure tin deposits of different thickness were obtained on a copper and brass substrates using methane sulfonic industrial bath. The deposits were compressed by a steel bearing ball forming imprint on the surface. The microstructure of tin whiskers obtained at the boundary of each imprint, their length and number were studied using both light and scanning electron microscopy. It was shown that the most intensive formation and growth of whiskers was observed in the first two hours. In general, brass substrate was shown to be more prone to whisker formation than copper independently of the tin coating thickness. The results have been compared with industrial bright tin finish on control unit socket leads and proposals have been made as to modification of the production process in order to minimize the risk of whiskering.
9
Content available The Effect Of Void Formation On The Reliability Of ED-XRF Measurements In Lead-Free Reflow Soldering
Koncz-Horváth D., Gergely G., Gacsi Z.
Archives of Metallurgy and Materials
|
2015
|
Vol. 60, iss. 2B
1445--1448
EN
In lead-free reflow soldering, the presence of voids should be taken into account. For this reason, the effect of the applied heating profiles was examined via the characterization of voids in galvanic and immersion Sn coatings. According to EU Directive 2002/95/EC, the screening of Pb element of reflow soldering (i.e. of electrical and electronic equipment) is necessary; and the practical implementation of this measurement is largely affected by the characteristics of the solder (i.e. the presence of voids and the inhomogeneity of the solder). Comparing the results of the above two coating methods, it was found that by chemical coating more voids were formed and the detected lead content was higher than for galvanic Sn. The standard deviation of Ag and Cu concentrations was mainly influenced by the appearance of large compounds in the second case, while with chemical coating, no large compounds were formed due to the elevated number of voids.
10
Content available Microstructure And Mechanical Properties Of Al-WC Composites
Simon A., Lipusz D., Baumli P., Balint P., Kaptay G., Gergely G., Sfikas S., Lekatou A., Karantzalis A., Gacsi Z.
Archives of Metallurgy and Materials
|
2015
|
Vol. 60, iss. 2B
1517--1521
EN
The scope of the research work is the production and characterization of Al matrix composites reinforced with WC ceramic nanoparticles. The synthesis process was powder metallurgy. The produced composites were examined as far as their microstructure and mechanical properties (resistance to wear, micro/macrohardness). Intermetallic phases (Al12W and Al2Cu) were identified in the microstrucutre. Al4C3 was not detected in the composites. Adding more than 5 wt% WC to the aluminum, microhardness and wear resistance exceed the values of Al alloy. Composites having weak interface bond performed the highest wear rate.
11
Content available Investigation Of Intermetallic Compounds In Sn-Cu-Ni Lead-Free Solders
Nagy E., Kristaly F., Gyenes A., Gacsi Z.
Archives of Metallurgy and Materials
|
2015
|
Vol. 60, iss. 2B
1511--1515
EN
Interfacial intermetallic compounds (IMC) play an important role in Sn-Cu lead-free soldering. The size and morphology of the intermetallic compounds formed between the lead-free solder and the Cu substrate have a significant effect on the mechanical strength of the solder joint. In the soldering process of Sn-Cu alloys, Cu6Sn5 intermetallic compounds are formed. The complex structural behaviour of Cu6Sn5 IMC is temperature- and composition-dependent and it is long since subject to scientific research. The Cu6Sn5 phase basically exists in two crystal structures: hexagonal η-Cu6Sn5 (at temperatures above 186°C) and monoclinic η’-Cu6Sn5 (at lower temperatures). In the presence of Ni in the solder, the η-η’ transformation does not occur, therefore, the η-Cu6Sn5 phase remains stable. In this study the role of Ni in the (Cu,Ni)6Sn5 intermetallic compound in Sn-Cu lead-free solders was examined. Sn-Cu alloys with different Cu content (0.5 to 1 mass%) were modified through Ni addition. The morphology of the intermetallic compounds of the modified Sn-Cu alloys was investigated by optical microscopy (OM) and scanning electron microscopy (SEM), the IMC phases were examined with X-ray diffraction method (XRD).
12
Content available Effects Of Nickel On The Microstructure And The Mechanical Properties Of Sn-0.7Cu Lead-Free Solders
Gyenes A., Simon A., Lanszki P., Gacsi Z.
Archives of Metallurgy and Materials
|
2015
|
Vol. 60, iss. 2B
1449--1454
EN
This paper investigates the effects of small amount nickel addition (0, 200, 400, 800, 1800 ppm) on the microstructure and the mechanical properties of Sn-0.7Cu lead-free solder alloys. It is known that even ppm level Ni additions have significant effects on the microstructure of Sn-Cu solder alloys. Ni suppresses the growth of β-Sn dendrites in favour of eutectic formation. As the nickel content increases, the microstructure undergoes a morphological evolution from hypoeutectic through fully eutectic to hypereutectic. Along with these transformations, the mechanical properties of the alloy also significantly change. Based on the experimental results presented in this paper, the Sn-0.7Cu solder achieves maximum strength at the addition level of 800 ppm Ni, when the microstructure becomes fully eutectic.
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