The computational intelligence tool has major contribution to analyse the properties of materials without much experimentation. The B4C particles are used to improve the quality of the strength of materials. With respect to the percentage of these particles used in the micro and nano, composites may fix the mechanical properties. The different combinations of input parameters determine the characteristics of raw materials. The load, content of B4C particles with 0%, 2%, 4%, 6%, 8% and 10% will determine the wear behaviour like CoF, wear rate etc. The properties of materials like stress, strain, % of elongation and impact energy are studied. The temperature based CoF and wear rate is analysed. The temperature may vary between 30°C, 100°C and 200°C. In addition, the CoF and wear rate of materials are predicted with respect to load, weight % of B4C and nano hexagonal boron nitride %. The intelligent tools like Neural Networks (BPNN, RBNN, FL and Decision tree) are applied to analyse these characteristics of micro / nano composites with the inclusion of B4C particles and nano hBN % without physically conducting the experiments in the Lab. The material properties will be classified with respect to the range of input parameters using the computational model.
The paper presents the results of research on the production and application of sintered copper matrix composite reinforced with titaniumcopper intermetallic phases. Cu- Ti composites were fabricated by powder metallurgy. The starting materials for obtaining the sintered composites were commercial powders of copper and titanium. Experiments were carried out on specimens containing 2.5, 5, 7.5 and 10 % of titanium by weight. Finished powders mixtures containing appropriate quantities of titanium were subjected to single pressing with a hydraulic press at a compaction pressure of 620 MPa. Obtained samples were subjected to sintering process at 880 °C in an atmosphere of dissociated ammonia. The sintering time was 6 hours. The introduction of titanium into copper resulted in the formation of many particles containing intermetallic phases. The obtained sinters were subjected to hardness, density and electrical conductivity measurements. Observations of the microstructure on metallographic specimens made from the sintered compacts were also performed using a optical microscope. An analysis of the chemical composition (EDS) of the obtained composites was also performed using a scanning electron microscope. Microstructural investigations by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) showed that after 6 hours of sintering at 880°C intermetallic compounds: TiCu, TiCu2, TiCu4, Ti2Cu3, Ti3Cu4 were formed. The hardness increased in comparison with a sample made of pure copper whereas density and electrical conductivity decreased. The aim of this work was to fabricate copper matrix composites reinforced with titanium particles containing copper- titanium intermetallic phases using powder metallurgy technology and determine the influence of the titanium particles on the properties of the sintered compacts and, finally, analyse the potentials application for friction materials or electric motors brushes.
In the present paper, elemental Fe, Cr and Ni powders were used to fabricate nano-structured duplex and ferritic stainless steel powders by using high energy planetary ball milling. We have studied the effect of milling atmosphere like wet (toluene) and dry (argon) milling of elemental Fe-18Cr-13Ni (duplex) and Fe-17Cr-1Ni (ferritic) powders for 10 h in a dual drive planetary mill. Stearic acid of 1wt. % was added during milling to avoid agglomeration. The dry and wet milled duplex and ferritic stainless steel powders were characterized by XRD, SEM and particle size analysis techniques. We have found that both the milling atmospheres have great influence in controlling the final particle morphology, size and phase evolution during milling. It was reported that dry milling is more effective in reducing particle size than the wet milling. The Nelson-Riley method of extrapolation was used to calculate the precise lattice parameter and Williamson-Hall method was used to calculate the crystallite size and lattice strain of both the stainless steel milled in argon atmosphere. Dry milled duplex and ferritic stainless steel were then consolidated by conventional sintering method at 1100, 1200 and 1300°C temperatures under argon atmosphere for 1 hour.
The Nb-Si based in-situ composite was produced by resistive sintering (RS) technique. In order to identify present phases, X-ray diffraction (XRD) analysis was used on the composite. XRD analysis revealed that the composite was composed of Nb solid solution (Nbss) and α-Nb5Si3 phases. The microstructure of the composite was characterized by using a scanning electron microscope (SEM). The energy-dispersive spectroscopy (EDS) was performed for the micro-analysis of the chemical species. SEM-EDS analyses show that the microstructure of composite consists of Nbss, Nb5Si3 and small volume fraction of Ti-rich Nbss phases. The micro hardness of constituent phases of the composite was found to be as 593±19 and 1408±33 Hv0.1, respectively and its relative density was % 98.54.
Traditional press and sinter processes have gained in the last decades more and more importance in the manufacturing of high volume and precise mechanical components especially in the field of iron based powders. In recent years, the reductions of processing times and temperatures were spotted as critical targets to increase productivity and reduce energy consumption. Electric current assisted sintering (ECAS) technologies have always been seen as an alternative to traditional furnace based sintering techniques and have been the target of different researches with the specific purpose of reducing both operational times and costs. The aim of the present study is to investigate the effect of an innovative process called Electro Sinter Forging (ESF) applied to CuSn15 powders. Thanks to a very short processing time (less than 1 second to densify loose powders), this process is able to retain a very small grain size, thus enhancing mechanical properties of the processed materials. Furthermore, to the authors knowledge, cold – rolled electro – sinter – forged alloys has never been investigated before. First of all, bars were electro – sinter – forged and subsequently characterized in the as sinter – forged condition. The observation of microstructure evidenced an extremely fine microstructure and a reduced degree of porosity. Afterwards, bars were cold rolled after different reduction ratios; macrostructural integrity of the rolled bars was assessed before evaluating the effects of cold rolling on the sinter – forged microstructure.
The aim of the study was to indicate the influence of consolidation processes on microstructure and selected mechanical properties of powder metallurgy Ti-5Al-5Mo-5V-3Cr alloy, which was produced by blending of elemental powders method. Morphology of the mixture and its ingredients were examined using scanning electron microscopy. The consolidation of powders mixture was conducted using two approaches. The first consisted of the uniaxial hot pressing process, the second included two steps – uniaxial cold pressing process and sintering under argon protective atmosphere. Microstructural analysis was performed for both as-pressed compacts using light microscopy. Additionally, computed tomography studies were carried out, in order to examine the internal structure of compacts. Chosen mechanical properties, such as Vickers hardness and compression strength was also determined and compared. The conducted research proves that the proposed production method leads to obtain materials with no structural defects and relatively low porosity. Moreover, due to the proper selection of manufacturing parameters, favorable microstructures can be received, as well as mechanical properties, which are comparable to conventionally produced material with the corresponding chemical composition.
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.
Hot Isostatic Pressing elaboration of Norem02, an austenitic-ferritic hypereutectoid stainless steel, leads to the formation of an austenitic matrix with a mixture of acicular M7C3 and globular M23C6 carbides. The sintering tests, carried out by using an AISI 304L container, showed that the final microstructure and the carbides’ distribution of the HIPed Norem02 are strongly influenced by the process parameters (heating and cooling rate, sintering time, holding temperature and pressure) and by the particles’ size, microstructure and phase distribution of the initial powder. The morphological, crystallographic and chemical analysis of the sintered samples were completed by comprehension of the diffusion phenomena at the Norem02/304L interface, enabling the establishment of a correlation between elaboration process and final microstructure.
The present investigation has been made to assess the influence of B4C reinforced with Ti-6Al-4V matrix prepared by powder metallurgy route. High energy ball milling was used to prepare the composites. Cylindrical preforms were prepared using suitable die set assembly. The green preforms were sintered in the muffle furnace at 900°C for 1 h. Further the preforms were cooled inside the furnace till the room temperature has attained. SEM with EDS mapping analysis was used to evaluate the morphology and elemental confirmation of the prepared composite. The density and hardness of the samples are determined using Archimedes principle and Rockwell hardness testing machine. The wear resistance of the samples was determined by employing a pin on disc apparatus. The hardness of the composites (Ti-6Al-4V /10B4C) was increased while comparing to the base material (Ti-6Al-4V) which is attributed to the presence of hard ceramic phase. Response Surface Methodology (RSM) five level central composite design approach was accustomed and it minimised the amount of experimental conditions and developed mathematical models among the key process parameters namely wt. % of B4C, applied load and sliding distances to forecast the abrasive response of Specific Wear Rate (SWR) and Coefficient of Friction (CoF). Analysis of variance was used to check the validity of the developed model. The optimum parameters of specific wear rate and coefficient of friction were identified.
The present investigation aims at fabricating a functionally graded Al-6Cr-Y2O3 composite and its microstructural and property characterization. Al-6Cr-alloys with varying percentage of Y2O3 (5-10 vol. %) have been used to fabricate FGM by powder metallurgy route. The samples were subsequently subjected to solution treatment at 610°C for 4 h followed by artificially aged at 310°C for 4 h. The microstructure, hardness and wear behavior of these FGM have been evaluated. FGM exhibited superior hardness (360 ± 5 VHN) as compared to the unprocessed composites (220 ± 5 VHN) due to the uniform dispersion of Y2O3 particles. Wear resistance of Al-6Cr-10 Y2O3 FGM were compared that of with pure Al-6Cr alloy by dry abrasive wear test. Al-6Cr-10 Y2O3 FGM composites were found to exhibit higher wear resistance with the minimum wear rate of 0.009 mm3/m compared to the Al- 6Cr alloy wear rate 0.02 mm3/m.