Wyniki wyszukiwania - BazTech

1

Effect of major alloying elements Zn and Mg on microstructure and microhardness of AA7075 alloys and their composites

Mittal Prachi, Verma Ishu, Tomar Amit, Mahato Jayanta Kumar

Composites Theory and Practice

|

2025

|

R. 25, nr 2

90-101

EN

The present research work focuses on studying the effect of the major alloying elements on the microstructure and hardness of 7xxx series aluminium alloys and their composites. AA7075 aluminium alloy was used as the base material and different weight percentages of alloying elements zinc (Zn) and magnesium (Mg) were added at ratios 1:1, 2:1 and 3:1 to the base material. Afterwards, the modified aluminium alloys were used as matrix materials for the fabrication of aluminium alloy matrix composites (AAMCs) by adding different weight fractions of silicon carbide (SiC) as reinforcement material. Both the alloys and the AAMCs were fabricated by means of stir casting. XRD, SEM and EDX analysis of the modified aluminium alloys and their composites were carried out. Microstructures of the modified aluminium alloys and AAMCs were observed and the grain sizes were measured according to ASTM standards. Hardness tests of the fabricated specimens were carried out using Vickers microhardness testers and the hardness values were measured utilising the integrated software. It was observed that equiaxed grain structures were formed in both the modified Al alloys and their composites, indicating successful fabrication by means of the casting process; however, the average grain sizes of the fabricated specimens are dependent on the combination of wt% of reinforce ment and the composition of the Al alloys. Interestingly, a positive correlation with the weight percent ratio of Zn and Mg in the AA7075 was observed, indicating the potential for fine-tuning of the mechanical properties through proper selection of the alloying elements. It was also observed that the microhardness of the AAMCs fabricated with the mod ified Al alloys exhibits consistent improvement with an increasing weight fraction of SiC reinforcement, irrespective of the weight percentage ratio of the added Zn and Mg combination.

2

Properties and strengthening mechanisms of nickel matrix composites reinforced with high-speed steel particles

Konieczny Marek

Composites Theory and Practice

|

2024

|

R. 24, nr 2

116--122

EN

Nickel matrix composites reinforced with T15 high-speed steel (HSS) particles were prepared using powder metallurgy. A systematic investigation was conducted into the effects of the sintering temperature and T15 HSS particle content on the microstructure and properties of the composites. The results indicate that the grain size of the nickel in the composites was effectively refined by the addition of T15 HSS particles in comparison to the pure sintered nickel. It was also observed that the T15 HSS particles, after sintering at all the used temperatures (850, 900 or 950 °C), were diffusion-bonded to the nickel matrix. There were two distinct layers between the reinforced particles and the nickel matrix: the solid solution of elements in nickel and the FeNi3 intermetallic compound, whose thickness slowly grows with the increase in sintering temperature. Also, as the sintering temperature was incremented, the relative density and hardness of the composites gradually rose. When sintered at 950 °C, the Ni+20 wt.%T15 composite achieved a maximum hardness of 135 HB, which was about 52 % higher than that of the pure sintered nickel. The introduction of an increasing amount of T15 HSS particles combined with sintering resulted in a rise in the yield strength of the sintered composites. At all the investigated temperatures, as the T15 HSS particle content was increased, the compressive strength of the composites also gradually grew. Nonetheless, as the sintering temperature was raised from 850 to 950 °C, the compressive strength of the composites initially increased and then decreased. The composite containing 20 wt.%T15 HSS particles sintered at 900 °C achieved the highest compressive strength of 445 MPa, which was about 50 % higher than that of the pure sintered nickel. Additionally, the primary contributions of strengthening mechanisms such as load transfer, grain refinement and thermal expansion mismatch to the mechanical properties of the Ni+T15 HSS composites were analyzed.

3

Microstructure and Mechanical Properties of the EN AC-AlSi12CuNiMg Alloy and AlSi Composite Reinforced with SiC Particles

Sirata Gotfila G., Wacławiak K., Dolata A. J.

Archives of Foundry Engineering

|

2024

|

Vol. 24, iss. 2

50--59

EN

There is growing interest in developing more advanced materials, as conventional materials are unable to meet the demands of the automotive, aerospace, and military industries. To meet the needs of these sectors, the use of advanced materials with superior properties, such as metal matrix composites, is essential. This paper discusses the evaluation of microstructural and mechanical properties of conventional eutectic EN AC-AlSi12CuNiMg aluminum alloy (AlSi12) and advanced composite based on EN AC-AlSi12CuNiMg alloy matrix with 10 wt% SiC particle reinforcement (AlSi12/10SiCp). The microstructure of these materials was investigated with the help of metallographic techniques, specifically using a light microscope (LM) and a scanning electron microscope (SEM). The results of the microstructural analysis show that the SiC particles are uniformly distributed in the matrix. The results of the mechanical tests indicate that the tensile properties and hardness of the AlSi12/10SiCp composite are significantly higher than those of the unreinforced eutectic alloy. For AlSi12/10SiCp composite, the tensile strength is 21% higher, the yield strength is 16% higher, the modulus of elasticity is 20% higher, and the hardness is 11% higher than unreinforced matrix alloy. However, the unreinforced AlSi12 alloy has a percentage elongation that is 16% higher than the composite material. This shows that the AlSi12/10SiCp composite has a lower ductility than the unreinforced AlSi12 alloy. The tensile specimens of the tested composite broke apart in a brittle manner with no discernible neck development, in contrast to the matrix specimens, which broke apart in a ductile manner with very little discernible neck formation.

4

Effect of Stir Casting Process Parameters and Stirrer Blade Geometry on Mechanical Properties of Al MMCs - A Review

Morsiya Chintan, Pandya Shailesh

Archives of Metallurgy and Materials

|

2023

|

Vol. 68, iss. 4

1473--1495

EN

Aluminium matrix composites offer a combination of properties such as lower weight, higher strength, higher wear resistance and many more. The stir casting process is easy to use, involves low cost and is suitable for mass production compared to other manufacturing processes. An in-depth look at recently manufactured aluminium matrix composites and their impact on particle distribution, porosity, wettability, microstructure and mechanical properties of Al matrix composites have all been studied in relation to stirring parameters. Several significant concerns have been raised about the sample’s poor wettability, porosity and particle distribution. Mechanical, thermal, and tribological properties are frequently studied in conjunction with variations in reinforcement proportion but few studies on the effect of stirrer blade design and parameters such as stirrer shape, dimensions and position have been reported. To study the effect of stirrer blade design on particle distribution, computational fluid dynamics is used by researchers. Reported multiphysics models were k-ε model and the k-ω model for simulation. It is necessary to analyse these models to determine which one best solves the real-time problem. Stirrer design selection and analysis of its effect on particle distribution using simulation, while taking underlying physics into account, can be well-thought-out as a future area of research in the widely adopted stir casting field.

5

Effects of Hard Oxides Reinforcing of Iron-Based MMCs on the Surface Topography Features after Finish Turning

Maruda Radosław, Leksycki Kamil, Feldshtein Eugene, Sąsiadek Eryk, Szczotkarz Natalia, Odważna Magdalena, Ochał Kamil, Gradzik Andrzej

Advances in Science and Technology. Research Journal

|

2023

|

Vol. 17, no. 1

15--22

EN

Effects of Hard Oxides Reinforcing of Iron-Based MMCs on the Surface Topography Features after Finish Turning

6

In-situ metal matrix composites development for additive manufacturing: a perspective

Essien U. A., Vaudreuil S.

Journal of Achievements in Materials and Manufacturing Engineering

|

2022

|

Vol. 111, nr 2

78--85

EN

Purpose: This paper presents an overview on some ceramic materials capable of achieving in-situ reinforcements in Al/Al-alloy metal matrix composites (MMCs) during laser processing. It also presents perspective on further exploitation of the in-situ reinforcement capabilities for high quality MMCs feedstock material development. Design/methodology/approach: The approach utilized in writing this paper encompasses the review of relevant literature on additive manufacturing (AM) of MMCs. Findings: It is widely accepted that the in-situ reinforcement approach has proven to be more advantageous than the ex-situ approach. Though there are still some challenges like the formation of detremental phases and the evaporation of low melting temperature elements, the in-situ reinforcement approach can be used to tailor design composite powder feedstock materials for the AM of MMCs. The preprocessing or tailor-designing in-situ metal matrix composite powder before laser melting into desired components holds more promises for metal additive manufacturing. Practical implications: The need for the development of MMCs powder feedstock that can be directly fabricated using suitable AM technique without prior powder processing like blending or mechanical alloying has not yet been addressed Therefore, having a pre-processed in-situ reinforced MMC feedstock powder can encourage easy fabrication of MMC and other advantages of AM technologies powder recycling. Originality/value: The idea explained in this article is relevant to materials development for AM processing of metal matrix composite. This paper has pointed out future trends for MMCs materials feedstock powder development and new ideas for further exploitation of MMCs and AM technologies. The advantages of tailor-designing composite powders other than merely mixing them has been emphasized.

7

Synthesis and Characterization of Bioceramics Reinforced Aluminium Matrix Composites

Bhuvaneswari V., Rajeshkumar L., Saravanakumar R., Balaji D.

Archives of Metallurgy and Materials

|

2022

|

Vol. 67, iss. 4

1217--1226

EN

Current work attempts to fabricate aluminium alloy AA2219 metal matrix composite (AMC) reinforced with natural bio-based sea shell powder (SSP) which is a ceramic material, in view of improving the mechanical and tribological properties. SSP was characterized by X-Ray Diffraction (XRD) to assess its chemical constituents and particle size. Stir casting route was adopted for fabricating AMCs reinforced with 1, 2 and 3 wt.% of SSP. Energy Dispersive X-ray Spectroscopy (EDS) was used to analyse the formation of secondary elements during casting and scanning electron microscopy (SEM) was used analyze the surface morphology of the composite specimen before and after tribological tests. Hardness, Compressive strength and tribological properties were evaluated using appropriate tests and corresponding ASTM standards. Characterization methods revealed that the formation of secondary elements was very low at 3 wt.% of SSP when compared with other compositions. Hardness and compressive strength was found to be maximum for 3 wt.% of SSP while the specific wear rate and coefficient of friction values were found to be lesser for the same composite when compared with the unreinforced alloy and were on par with the AA2219 composites containing synthetic reinforcements.

8

Effect of Zeolite Addition on the Production of a Cast Porous Composite Based on AC-AlSi11 Silumin

Borowiecka-Jamrożek Joanna, Kargul Marcin

Archives of Foundry Engineering

|

2022

|

Vol. 22, iss. 4

96--101

EN

The paper presents the application of the casting method for the production of porous composites, called syntactic foams, of the casting alloy - solid particles type. This method was used to produce composites based on Al alloys reinforced with particles of clinoptilolite, a natural mineral from the zeolite group. Before the casting process, tests were carried out on the morphology, physicochemical properties and chemical composition of the zeolite, which was obtained from a rock called zeolite tuff, mined in a quarry in Kucin, (VSK PRO-ZEO s.r.o., Slovakia). Observations of the microstructure of the produced composites were also carried out using a scanning electron microscope. Diffractometric tests of zeolite rock as delivered for research and of the produced samples reinforced with zeolite particles were also carried out. Initial studies of the density and porosity of the produced composites were performed. The usefulness of the presented method of composite production was assessed on the basis of the conducted structural tests, with particular emphasis on the particle distribution in the alloy matrix.

9

Impact of heat treatment on the mechanical performance of hot extruded Al6061-BN reinforced metal matrix composites

Mukesh Y. B., Naik Prem Kumar, R Raghavendra Rao, Vishwanatha N. R., Prema N. S., Girish H. N., Laxmana Naik L., Madhusudan Puttaswamy

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2021

|

Vol. 69, nr 3

art. no. e137014

EN

Boron nitride (BN) reinforced Al6061 aluminum-based composites are synthesized by conventional stir casting method followed by exposure to hot extrusion. The optical images confirmed the distribution of BN nanoparticles in the aluminum alloy matrix. The concentration of BN is varied from (0.5, 1.5, 3, 4.5, 6, 7.5, and 9 wt%) in the composites and its effect on the tensile strength was investigated. The results revealed that both extruded and heat-treated composites specimens showed enhanced toughness and tensile strength by increasing BN nanoparticle concentration. The heat-treated composite samples showed lower flexibility of up to 40%, and further, it exhibited 37% greater hardness and 32% enhancement in tensile strength over the extruded sample. The tensile properties of Al6061-BN composites were evaluated by temperature-dependent internal friction (TDIF) analysis and the results showed that the as-prepared composite's strength increased with temperature.

10

Review on properties of aluminium metal matrix composites

Subramaniam Balasubramani, Purusothaman Vijay Rengaraj, Karuppusamy Sibi Mayuran, Ganesh Shree Hari, Markandan Raj Kumar

Journal of Mechanical and Energy Engineering

|

2020

|

Vol. 4, No 1

57--66

EN

Nowadays, the global industries producing mechanical components are moving towards the usage of composites to reduce weight at the same time without compromising with characteristics of the material being used. This new combination of material provides specific desired properties when combined with various reinforcement materials like SiC, B4C, Al2O3, MgO etc., It is widely used in various industries like aerospace, automobile and marine industries. This property specific tailorable metal matrix composite with Al7075 as the base material can be fabricated using various techniques such as stir casting, high end ball milling, ultrasonic assisted casting, powder metallurgy, squeeze casting friction stir casting etc., out of which stir casting method is preferred by many researchers as stir casting method is seen to provide better distribution of reinforcement particles throughout the metal matrix. It is evident from the research of various authors that when the base material Al7075 is reinforced with the above-mentioned ceramic, it is found that there is a decrease in density and increase in hardness, compressive strength and wear resistance. Here, both physical and mechanical behaviour of aluminium reinforced composites with the effect of the particle size changes, effects after reinforcement and other processing and fabrication methods have been discussed.

11

Recent studies on particulate reinforced AZ91 magnesium composites fabricated by stir casting - a review

Matta Anil Kumar, Koka Naga Sai Suman, Devarakonda Sameer Kumar

Journal of Mechanical and Energy Engineering

|

2020

|

Vol. 4, No 2

115--126

EN

Magnesium Metal Matrix Composites (Mg MMC) have been the focus of consideration by many researchers for the past few years. Many applications of Mg MMCs were evolved in less span of time in the automotive and aerospace sector to capture the benefit of high strength to weight ratio along with improved corrosion resistance. However, the performance of these materials in critical conditions is significantly influenced by several factors including the fabrication methods used for processing the composites. Most of the papers addressed all the manufacturing strategies of Mg MMC but no paper was recognized as a dedicated source for magnesium composites prepared through STIR casting process. Since STIR casting is the least expensive and most common process in the preparation of composites, this paper reviews particulate based Mg MMCs fabricated with STIR casting technology. AZ91 series alloys are considered as the matrix material while the effect of different particle reinforcements, sizes, weight fractions on mechanical and tribological responses are elaborated in support with micro structural examinations. Technical difficulties and latest innovations happened during the last decade in making Mg MMCs as high performance material are also presented.

12

Wytwarzanie i mikrostruktura osadzanych elektrolitycznie stopów Ni-Co i kompozytów TiO2 / Ni-Co

Ledwig Piotr, Dubiel Beata, Kopia Agnieszka

Hutnik, Wiadomości Hutnicze

|

2020

|

Vol. 87, nr 4

107--113

PL

Stopy Ni-Co oraz kompozyty TiO2/Ni-Co osadzono elektrolitycznie z kąpieli siarczanowo-cytrynianowych o względnej zawartości jonów Co:Ni równej 1:49, 1:24 i 1:9 stosując gęstości prądu 2,5, 5 i 7,5 A/dm2. Wpływ parametrów osadzania na morfologię powierzchni, mikrostrukturę, skład chemiczny i skład fazowy zbadano za pomocą skaningowej i transmisyjnej mikroskopii elektronowej, spektroskopii dyspersji energii charakterystycznego promieniowania rentgenowskiego oraz dyfrakcji promieniowania rentgenowskiego. Wytworzone kompozyty charakteryzowały się globularną morfologią i nanokrystaliczną mikrostrukturą. Wykazano, że w osnowie kompozytów występują pojedyncze nanocząstki oraz aglomeraty TiO2. Zawartość TiO2 w kompozytach wynosiła około 4% mas. Stwierdzono, że wielkość ziarna kompozytów TiO2/Ni-Co zależy od obecności fazy umacniającej, warunków prądowych podczas osadzania oraz stężenia Co w osnowie Ni-Co.

EN

TiO2/Ni-Co composites were electrodeposited from citrate-sulfate bath with varying Ni:Co ratios. Effect of deposition conditions on chemical composition, surface morphology, microstructure and phase composition were investigated using scanning and transmission electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. Manufactured composites were characterized by typical cauliflower surface morphology and nanocrystalline structure. Nanocrystalline TiO2 particles were embedded in the Ni-Co matrix both in the form of dispersive nanoparticles and clusters. The concentration of nc-TiO2 in composites was about 4 wt. %. Grain size of TiO2/Ni-Co composites depended on the content of strengthening phase, deposition current conditions and Co concentration in the Ni-Co matrix.

13

Effect of upgraded field assisted sintering technology on microstructure of NiAl/CrB2 composites

Szlezynger Maciej, Maj Łukasz, Pomorska Małgorzata, Morgiel Jerzy, Jach Katarzyna, Rosinski Marcin

Composites Theory and Practice

|

2020

|

R. 20, nr 1

7--10

EN

The method of fabricating metal matrix composites plays a crucial role in obtaining dense materials characterized by high wear resistance. The present work describes an attempt to produce NiAl/CrB2 composites using the next generation spark plasma sintering (SPS) method, i.e. upgraded field assisted sintering technology (U-FAST) technique. Microstructure characterization was performed by means of scanning (SEM) and transmission (TEM) electron microscopy. The SEM microstructure investigations of the NiAl model material proved practically full densification of the material sintered at 1200°C and 1300°C, even if remnants of surplus nickel were observed at the boundaries of rounded NiAl grains. The NiAl/CrB2 composites, besides fused NiAl and CrB2 grains, showed the presence of a raised level of nickel also at the grain boundaries. The TEM microstructure observations helped to establish that even if the grain boundaries were pinned by nickel-rich precipitates, some increase in grain growth took place, as evidenced by the fact that strings of smaller precipitates were also visible outside the matrix grain boundaries. All these microstructure investigations indicate that the newly elaborated U-FAST technique is evidently capable of producing compacts free of porosity at lower temperatures and during a shorter time than solid hot pressing or vacuum sintering in a semiliquid state.

14

Study of the microstructure and mechanical characteristics of AZ91–SiCp composites fabricated by stir casting

Saleh Bassiouny, Jiang Jinghua, Fathi Reham, Xu Qiong, Wang Lisha, Ma Aibin

Archives of Civil and Mechanical Engineering

|

2020

|

Vol. 20, no. 3

102--115

EN

In recent years, the composite materials have been very desirable by researchers for many engineering applications such as aviation and biomedical because of the tremendous characteristics of magnesium matrix metal composite. This current investigation aims to develop the AZ91/SiCp composites with various weight fractions (0, 2.5, 5 and 10 wt%) of silicon carbide particles via the stir casting method. The effect of SiC particles content on microstructure, mechanical and wear behaviour was investigated. The optical microscope, scanning electron microscopy and EDX analyses were utilized to detect the distribution of hard particles as well as the interface between the alloy and particles. Based on the findings, the homogeneous distribution of particles, refinement of grains in addition to good bonding between AZ91 alloy and particles have been achieved in produced composites. Therefore, the mechanical characteristics and wear performance are improved in composites compared with the unreinforced alloy. Moreover, these results suggest that for applications demanding high mechanical properties and wear resistance the AZ91/SiCp will be effective composites.

15

Damage evolution in AA2124/SiC metal matrix composites under tension with consecutive unloadings

Rutecka A., Kursa M., Pietrzak K., Kowalczyk-Gajewska K., Makowska K., Wyszkowski M.

Archives of Civil and Mechanical Engineering

|

2020

|

Vol. 20, no. 4

560--577

EN

Nonlinear properties of metal matrix composites (MMCs) are studied. The research combines results of loading–unloading tensile tests, microstructural observations and numerical predictions by means of micromechanical mean-field models. AA2124/SiC metal matrix composites with SiC particles, produced by the Aerospace Metal Composites Ltd. (AMC) are investigated. The aluminum matrix is reinforced with 17% and 25% of SiC particles. The best conditions to evaluate the current elastic stiffness modulus have been assessed. Tensile tests were carried out with consecutive unloading loops to obtain actual tensile modulus and study degradation of elastic properties of the composites. The microstructure examination by scanning electron microscopy (SEM) showed a variety of phenomena occurring during composite deformation and possible sources of elastic stiffness reduction and damage evolution have been indicated. Two micromechanical approaches, the incremental Mori–Tanaka (MT) and self-consistent (SC) schemes, are applied to estimate effective properties of the composites. The standard formulations are extended to take into account elasto-plasticity and damage development in the metal phase. The method of direct linearization performed for the tangent or secant stiffness moduli is formulated. Predictions of both approaches are compared with experimental results of tensile tests in the elastic–plastic regime. The question is addressed how to perform the micromechanical modelling if the actual stress–strain curve of metal matrix is unknown.

16

The Influence of Glassy Carbon ond Its Forms on Tribological Properties of Aluminium Matrix Composites

Myalski Jerzy, Posmyk Andrzej, Hekner Bartosz, Godzierz Marcin

Tribologia

|

2019

|

nr 3

79--87

EN

Carbon with an amorphous structure was used as a component to modify the tribological properties of engineering plastics. Its construction allows the formation of carbon-based wear products during friction, adhesively bonded to the surface of cooperating machine parts, acting as a solid lubricant. The work compares the tribological properties of two groups of composites with an aluminium alloy matrix in which glassy carbon appeared in the form of particles and an open cell foam fulfilling the role of strengthening the matrix. The use of spatial structures of reinforcement provides, in comparison with the strengthening of particles, homogeneity of carbon distribution in the entire volume of the composite. The tests carried out on a pin-disc tester showed that the use of spatial carbon structures in the composite ensures a greater coefficient of friction stability than when reinforcing with particles, and the coefficient of friction with a small proportion of carbon foams (about 1 wt%) is comparable with the coefficient of friction in the contact with composites containing 5-10% carbon particles in granular form.

PL

Węgiel o strukturze amorficznej został wykorzystywany, jako komponent do modyfikacji właściwości tribologicznych tworzyw konstrukcyjnych. Jego budowa pozwala na tworzenie się w trakcie tarcia węglowych produktów zużycia, połączonych adhezyjnie z powierzchnią współpracujących części maszyn, pełniących funkcję smaru stałego. W pracy porównano właściwości tribologiczne dwóch grup kompozytów z osnową ze stopu aluminium, w których węgiel szklisty występował w postaci cząstek oraz piany otwartokomórkowej pełniącej rolę umocnienia osnowy. Wykorzystanie przestrzennych struktur zbrojenia zapewnia, w porównaniu z umocnieniem cząstkami, homogeniczność rozkładu węgla w całej objętości kompozytu. Przeprowadzone badania na testerze pin-disc wykazały, że wykorzystanie w kompozycie przestrzennych struktur węglowych zapewnia większą stabilność współczynnika tarcia niż przy umocnieniu cząstkami, a współczynnik tarcia przy niewielkim udziale pian węglowych (około 1% cz. wag.) jest porównywalny ze współczynnikiem tarcia w skojarzeniu z kompozytami zawierającymi 5–10% cząstek węglowych w postaci ziarnistej.

17

Hybrydowa technologia HPDC&HSC

Dudek Piotr, Sobczak Jerzy J.

Prace Instytutu Odlewnictwa

|

2019

|

Vol. 59, no. 1

21--36

PL

W artykule przedstawiono rys historyczny oraz stan obecny technologii odlewania z wykorzystaniem ciśnienia zewnętrznego na przykładzie odlewania pod wysokim ciśnieniem (High Pressure Die Casting – HPDC) oraz prasowania w stanie ciekłym (Squeeze Casting – SC). Wykazano podobieństwa i różnice obu technologii oraz obszary wspólne, które zostały wykorzystane do budowy współczesnych, hybrydowych maszyn łączących cechy HPDC i SC. Ostatnie lata przyniosły rozwój konstrukcji maszyn ciśnieniowych, które umożliwiły hybrydyzację technologii z wysoką elastycznością procesu, polegającą na wyborze takiego sposobu przyłożenia ciśnienia zewnętrznego, w którym można pełniej wykorzystać jego wpływ jako czynnika termodynamicznego. Zaprezentowano doświadczenia w zakresie prasowania w stanie ciekłym i stało-ciekłym, uzyskane w badaniach prowadzonych w Instytucie Odlewnictwa w Krakowie.

EN

The article presents the history and current state of the technology of external pressure casting in the case of High Pressure Die Casting (HPDC) and Squeeze Casting (SC). The similarities and differences between the two technologies and the common areas that were used in the construction of modern hybrid machines combining the features of HPDC and SC were shown. Recent years have seen the development of pressure machine designs that have enabled the hybridisation of technologies with high flexibility of the process, consisting in the choice of such a method of applying external pressure in which its influence can be more effectively used as a thermodynamic factor. The following experiments were presented in the field of liquid and solid-liquid casting, obtained from research conducted at the Foundry Research Institute in Kraków.

18

Tribological behavior of AA7050-ZrSiO4 composites synthesized by stir casting technique

Sakthivelu S., Meignanamoorthy M., Ravichandran M., Sethusundaram P. P.

Mechanics and Mechanical Engineering

|

2019

|

Vol. 23, nr 1

198--201

EN

This research made an attempt to synthesize aluminum metal matrix composites through stir casting technique. The matrix material chosen in this study was AA7050 and the reinforcement material was ZrSiO4. The composites AA7050, AA7050-10%ZrSiO4, and AA7050-15%ZrSiO4 were used. The wear behavior of the aluminium matrix composites was investigated by using pin-on-disc tribometer. The advanced material has substantial development in tribological behavior when the reinforcement percentage is increased. From the experimental results, it was confirmed that sliding distance of 1200 m, applied load of 3 N and sliding speed of 2 m/s result in minimum wear loss and coefficient of friction, while adding 10%ZrSiO4 to the AA7050.

19

Toward understanding the origins of poor ductility in a metal-matrix composite processed by accumulative roll bonding (ARB)

Gharechomaghlu M., Mirzadeh H.

Archives of Civil and Mechanical Engineering

|

2019

|

Vol. 19, no. 4

958--966

EN

The importance of second phase particles has received less attention for metal-matrix composites (MMCs) processed by one of the most common severe plastic deformation (SPD) techniques known as accumulative roll bonding (ARB). Accordingly, the present work has been dedicated to the processing and evaluating the effects of ARB on the tensile properties, work-hardening behavior, distribution of particles, and fracture surface appearance of a typical Al-B4C particulate composite. It was found that bonding between the reinforcement and the matrix is not good enough to grant the effective strengthening effect. As a result, both tensile strength and ductility of ARB processed aluminum were higher than those of ARB processed Al-B4C composite. Moreover, by increasing ARB pass number, the tensile strength and total elongation of composites increased, where the latter was related to the enhancement of particle distribution, improvement of the particle/matrix interface, and enhancement of the work-hardening behavior. It was revealed that particle distribution affects the ductility but its effect on the tensile strength is less pronounced.

20

Mechanical, tribological and electrical properties of Cu-CNT composites fabricated by flake powder metallurgy method

Akbarpour M. R., Alipour S, Farvizi M., Kim H. S.

Archives of Civil and Mechanical Engineering

|

2019

|

Vol. 19, no. 3

694--706

EN

Cu-CNT composites were fabricated by a flake powder metallurgy method, and their microhardness, electrical conductivity, frictional and wear properties were investigated. Homogenous distribution of CNTs in fine-grained Cu matrix was obtained using this process. Microhardness increased with the addition of CNT vol% up to 8% to the Cu matrix, while the conductivity decreased to 79.2 IACS %. Results showed that CNTs play a major role in improving wear resistance by forming a CNT-rich film that acts as a solid lubricant layer. In the synthesized composites, Cu- 4 vol% CNT composite exhibited the best wear and friction properties. The dominant wear mechanisms for the Cu-CNT composites were plastic deformation, abrasion, and flake formation-spalling. Also, a newly modified correlation was proposed for the theoretical calculation of the friction coefficient of Cu-CNT composites consisting agglomerated CNTs.