Evaluation of mechanical behaviour and tensile failure analysis of 8 wt.% of nano B 4 C particles reinforced Al2214 alloy nano composites

. The microstructure and mechanical properties of Al2214-8 wt.% of 500nm sized B 4 C particles reinforced composites were studied in this study. By using a liquid metallurgical process, composites containing 8wt.% of B 4 C in Al2214 alloy were created. To increase the wettability and dispersion of the composites, forti ﬁ cation particles were warmed to 300 ° C and then added in groups of two into the vortex of liquid Al2214 alloy compound. ASTM standards were used to analyse the mechanical characteristics of Al2214 alloy and Al2214-8 wt.% of B 4 C composites. The distribution and presence of nano B 4 C particles in the Al2214 alloy matrix were con ﬁ rmed by microstructural analysis using SEM and EDS. XRD patterns indicated the presence of the B 4 C phases in Al2214 alloy composites. The addition of 8 wt.% of B 4 C particles to Al2214 alloy improved its hardness, ultimate, yield, and compression strength. Furthermore, the presence of B 4 C particles reduced the ductility of the Al2214 alloy. The tested materials were subjected to tensile fractography to determine the various fracture mechanisms.


Introduction
Bearings, piston rings, brake pads, clutches, couplings, and gears, among other things, must have a long service life, be reliable, and have minimal friction.These parts operating conditions vary depending on a variety of factors such as sliding speeds, weights, ambient conditions, and other factors.There is no single metal that can meet all of the requirements.As a result, it's critical to create a composite material with all of the necessary combinational properties to meet engineering criteria.Aluminium composites have gained worldwide attention in the field of research in military applications such as armour tanks, bullet proof jackets, automobile body parts, aeronautical applications, space, and the automotive industries due to their enriched possessions such as high strength, lightweight, and excellent wear resistance [1][2][3].Due to their superior strength-to-weight ratio, heat treatable aluminium alloys such as Al2214, Al6063, and Al7075 are often used, and metal matrix composites (MMCs) manufactured with these alloys have improved temperature stability [4,5].Aluminum metal matrix composites (AMMC) properties can be enhanced by selecting the appropriate reinforcing geometry, type, and shape, as well as the appropriate fabrication procedure [6,7].The addition of hard and stronger ceramic particles to a medium-strength, ductile, and low-stiffness metal matrix can improve the properties of the ceramic and the base matrix [8,9].The qualities of MMCs are largely determined by the processing method used.The processing approaches for manufacturing composites are determined by whether the reinforcement is added to the matrix in a solid or liquid state [10,11].Stir casting is a favoured processing technique for fabricating composites in the liquid state because of its flexibility, economy, and ability to create bulk quality production [12,13].The liquid state technique works on the premise of melting the matrix material, then adding reinforcement to the melt to get the desired dispersion [14].
There are a number of problems to consider when fabricating MMCs by stir casting, including wettability, porosity during solidification, and cluster due to nonuniformity [15].To achieve homogeneity, homogeneous reinforcement mixing must be concentrated.While fabricating, high wettability between two phases and good bonding must be optimised.Among the numerous matrix materials, Al and its alloys are widely used in the production of MMCs for industrial applications.Different combinations of Al based MMCs with different particles B 4 C, Al 2 O 3 , SiC, WC, and TiB 2 are used to generate MMCs with required qualities [16][17][18].Boron carbide is a hard ceramic particle that is utilised for high-temperature applications and is one of the most important hard ceramic particulate reinforcements for Al alloy matrixes [19].Boron carbide is a refractory metal with a specific density of 2.52 g/cc that is used in cutting tools, extrusion dies, and high-temperature drilling [20].
Using 500 nm sized B 4 C particles in an Al2214 alloy matrix, a limited investigation was carried out based on the available literature.Stir casting is used to make the Al2214 with 8 wt.% of B 4 C metal matrix composite.To avoid agglomeration, B 4 C particles are added to the aluminium melt in two phases.The prepared composites are next put through a series of mechanical testing.

Experimental details 2.1 Materials used
Al2214 alloy is a wrought alloy that can be processed in a secondary manner.Copper is the principal alloying element in Al2214, with a melting point of 660 °C and a density of 2.80 g/cm 3 .The Al2214 alloy is mostly employed in the transportation and aerospace industries, among other things.Al2214 is robust, corrosion-resistant, and has high raised temperature strength, as well as a high self-healing capability during the welding process.Al2214's chemical composition is shown in Table 1.
The reinforcement material is 500 nm boron carbide obtained from Speedfam Chennai Ltd. in India.The density of the reinforcement particle is 2.52 g/cm 3 , with a melting point of 3300 °C and a hardness of 3100-3600 kg/mm 2 .The SEM and EDS spectrum of B 4 C particles utilised to make the composites are shown in Figures 1 and 2.

Methodology and testing
The Al2214-B 4 C composites are made using the stir casting process.In a graphite crucible, a measured amount of Al2214 alloy is put.After that, the crucible is placed in the electric furnace.To melt the Al2214 alloy, the furnace is kept at 750 °C.B 4 C particles are roasted at 300 °C in a separate oven at the same time to reduce moisture content and promote wettability.Hexochlorthane [21], a degassing agent, is applied to the molten metal to prevent undesired gases [22].A unique two-step reinforcement addition approach is used to pour a known quantity of B 4 C particles into molten metal.The casting is then swirled for 5 min at 300 rpm with a mechanical stirrer made of zirconium coated material for a homogeneous mixture.The molten metal is put into the mould die right away.Cast iron is used to make the die.The cast iron die has a length of 120 mm and a diameter of 15 mm.To carry out the relevant testing, the castings are machined to ASTM standards.Figure 3 shows the composites that were prepared for the investigation.Following casting, the sample is processed for microstructural analysis using an electron microscope to determine the uniform distribution of B 4 C particles in the Al2214 alloy.Microstructure pictures of Al2214 alloy and Al2214-B 4 C composites are acquired.Microstructure specimen dimensions are 12 mm in dia., and 5 mm in height.300, 600, and 1000 grit paper are used to grind the specimen's surface.The surface is then polished on a polishing machine with a polishing paper for a smoother finish.Following that, the specimens are washed with distilled water to eliminate any foreign particles such as dirt or other impurities that may have accumulated on the polished surface.Keller's reagent [23] is used to etch the specimens to create a contrast surface.XRD studies are carried out by a PANALYTICAL XRD using Cu-K alpha radiation.The 2u range is selected such that all the intense peaks of the material phases predictable are covered.
The specimen is machined in accordance with ASTM standard E10 [24] for the hardness test.The Brinell hardness tester is used to test the hardness.The polished surface of the specimen is smooth.A 5 mm ball depression was made on the specimen, and a 250 kg force was applied.On the surface of the specimen, five indentation marks are made, and the findings are analysed.
The specimens are machined according to ASTM standard E8 [25] to assess the tensile behavior of as cast Al2214 alloy its B 4 C composites.To achieve precise findings, three samples are tested for tensile strength testing.The computer-integrated machine is used to test tensile strength, explore the behavior of Al2214-B 4 C composites under unidirectional tension, and study the influence of uniform distribution.The specimen measures overall length of 104, with gauge length of 45 mm, and 9 mm in gauge diameter.This tensile test can be used to study the mechanical behavior of cast alloys and composites in order to determine ultimate, yield, and elongation.Compression test is conducted as per ASTM E9 standard on specimen with dimensions of 15 mm diameter and 22.5 mm in length.Figure 4 shows the tensile test specimen.Because of the revolutionary two-stage technique used to create the composites; these particles are devoid of clustering.The presence of these nano B 4 C particles increases the Al2214 alloy's mechanical properties [26].

Results and discussion
The EDS spectrum of Al2214 alloy and 8 wt.percent nano B 4 C composites is shown in Figures 6a and 6b.Cu, along with Si, F, and Mg, is a key alloying ingredient in Al2214 alloy, as seen in Figure 6a.The EDS spectrum of Al2214-8 wt.% of B 4 C nano composites is also shown in Figure 6b.The occurrence of B 4 C particles in the Al2214 alloy in the form of B and C elements was detected in the EDS spectra of composites.The inclusion of B and C elements, as well as Zn, Mg, Fe, and Si, verifies the validity of the casting approach used to create the composites.
The Al2214 alloy and Al2214-8 wt.% of B 4 C composites are analysed using an X-Ray Diffractometer.The XRD pattern of Al2214 is given in Figure 7a; typically, aluminium phases are existing at various peaks, as seen in Figure 7a.At 39, 45, 65, and 79, the presence of Al phases is confirmed with varying intensities.At 39, the Al phase has the highest intensity.The XRD pattern of Al2214-8 wt.% of B 4 C composites is shown in Figure 7b.and incorporating such a high-hardness substantial into a soft medium helps to improve the hardness.In addition, because the thermal co-efficient mismatch between the Al2214 alloy and the B 4 C particles causes dislocation density, this approach causes higher strain hardening in the composites [27,28].The composites' hardness is increased through the strain hardening phenomenon.Figure 10 and Table 4 show the effect of B 4 C addition on the yield strength of Al2214 alloy.The strength of the Al2214 has been increased by 8 weight percent of B 4 C particles in the soft Al matrix, as shown in Figure 10.Al2214 alloy has yield strength of 174.5 MPa.In addition,  The ultimate and yield strength of Al2214 alloy were both improved with 8 wt.% of B 4 C particles, as shown in plots 9 and 10.The inclusion of the B 4 C element in the matrix increases the strength of Al alloy.The hard particle converts the Al matrix brittle, allowing it to withstand higher directed loads.These B 4 C bits operate as loadbearing elements in composites, enhancing the composites' strength.Furthermore, according to the Hall-Petch strengthening process, the insertion of tiny particles in the Al matrix reduces the grain size of the composites, which adds to the material's increased strength.The temperature mismatch between the Al2219 and the B 4 C particles is large, resulting in density dislocations according to the Orowan principle [29].Within the Al-B 4 C melt, the produced density dislocations cause strain hardening, which leads to the creation of increased strength [30].Chandrasekhar et al. [31] studied the nano B 4 C reinforced Al7475 alloy composites mechanical behavior.Al7475 alloy mechanical properties were improved the incorporation of nano particles.

Percentage elongation
The ductility of Al2214 alloy and Al2214 alloy with 8 wt.% of B 4 C nano composites is shown in Figure 11 and Table 5.According to the graph, ductility reduces by adding B 4 C in the matrix.The decrease in ductility is due to the presence of hard B 4 C particles in the matrix, as well as significant multidirectional stresses at the Al2214 alloy B 4 C contact, which prevents further material elongation.The sound bonding of Al and B 4 C particles, as well as the efficient transfer of applied load to a larger number of nano B 4 C particles.As a result of all of these effects, the elongation produced in Al2214 alloy À 8 wt.% of B 4 C composites is lower than in base amalgam.

Compression strength
Figure 12 and Table 6 depict the compression strength of Al2214 and Al2214 alloy with 8 wt.% of B 4 C particles reinforced composites.The existence of rigid particle phase increased the compression strength of the Al2214 matrix, according to the plot.Because these ceramics are tougher in nature, compressive strength is always used to determine the  strength of the carbide or oxide particles.The large degree of grain refinement gained with the inclusion of B 4 C, the incidence of evenly disseminated tougher components, and dislocation created due to the modulus mismatch and thermal expansion co-efficient can all be contributed to the Al-B 4 C composites' strength [32].According to the results of Figure 12, the effect of B 4 C content on compressive strength is significant.This demonstrates that B 4 C particles have a clear effect on the strength of Al-B 4 C composites.

Tensile fractography
SEM pictures of the breakage surfaces of Al2214 and Al2214 alloy with 8 wt.% of B 4 C composites are shown in Figures 13a and 13b.The good bonding between the Al2214 and the B 4 C reinforcement can be inferred from all of the tension fractured micrographs.The shattered surface of 500X magnification photos of Al2214 alloy is shown in Figure 13a.The ductile fracture is shown by the cracked surface of the as cast alloy, which has clear visibility of the grains.
Figure 13b shows the fractured surfaces of B 4 C reinforced composites, which have brittleness due to the presence of B 4 C reinforcement.Furthermore, the brittle fracture is directly connected to the composites' elongation.The ductility of the composites decreases as the weight percent of B 4 C particles increases, as discussed in the percentage elongation section.

3. 1
Microstructural StudiesScanning electron microphotographs of Al2214 alloy and composites with 8 wt.% of B 4 C particles are shown in Figures5a and 5b.The SEM picture of Al2214 alloy is shown in Figure5a.This denotes the absence of particles and the presence of clean grain boundaries.There are no voids or other casting flaws visible on the microscope.Microphotographs of Al2214-8 wt.% of B 4 C composite are shown in Figure5b.The B 4 C particles, which are observable in the micrographs, are found in 8 wt.% of B 4 C reinforced composites, according to the micrograph.

4 K.
Gopalan et al.: Manufacturing Rev. 9, 31 (2022) The various phases, such as Al and B 4 C, are shown in Figure7b.As previously said, Al phases are widely available at various 2 angles with varying intensities, whereas B 4 C particle phases are identified at 31 degrees, 38 degrees, and 50 degrees with varying intensities.

Figure 8 and
Figure 8 and Table 2 display the hardness of Al2214 alloy and Al2214 with 8% B 4 C composites.The plot shows that adding 8 wt.% of B 4 C particles to the Al2214 alloy improves its hardness.The hardness of the alloy as cast is 61.4 BHN, but after adding 8 wt.percent B 4 C particles, it is 95.6 BHN.The hardness of B 4 C composites using Al2214 alloy-8 wt.% improved by 55.7%.The incidence of hard B 4 C particles in the ductile matrix increases the hardness of Al2214 alloy.B 4 C particles have a hardness of 3300 BHN,and incorporating such a high-hardness substantial into a soft medium helps to improve the hardness.In addition, because the thermal co-efficient mismatch between the Al2214 alloy and the B 4 C particles causes dislocation density, this approach causes higher strain hardening in the composites[27,28].The composites' hardness is increased through the strain hardening phenomenon.

Figure 9 and
Figure 9 and Table 3 depict the effect of B 4 C addition on the strength of Al2214 alloy.The strength of the Al2214 alloy has been increased by adding 8 weight percent of B 4 C particles to the soft Al matrix, as shown in Figure 9. Al2214 alloy has an ultimate tensile strength of 224.8 MPa.In addition, the UTS of Al2214-8 wt.% of B 4 C composite is 311.5 MPa.After incorporating 8 wt.% of nano-sized B 4 C particles into Al2214 alloy, the UTS improved by 38.5%.Figure10and Table4show the effect of B 4 C addition on the yield strength of Al2214 alloy.The strength of the Al2214 has been increased by 8 weight percent of B 4 C particles in the soft Al matrix, as shown in Figure10.Al2214 alloy has yield strength of 174.5 MPa.In addition,

4 Conclusions
The Al2214 alloy with 8 wt.% of B 4 C metal composites were successfully synthesized using the stir casting method.SEM, EDS and XRD patterns were used to examine the microstructural characteristics of the produced Al2214 alloy and Al2214 alloy with 8 wt.% of B 4 C nano composites.SEM micrographs, EDS analysis and XRD patterns were used to show the distribution and existence of B 4 C nano particles in the Al2214 alloy metal composites.The results showed that with the addition of 8 wt.% of B 4 C nano content in the Al2214 alloy, there was increase in the ultimate, yield, and compression strength with a nominal drop in ductility.In unreinforced material, tensile fractured surfaces showed ductile mode fracture.Furthermore, 8 wt.% of B 4 C reinforced composites began to shatter in a brittle manner.

Table 2 .
Hardness of Al2214 alloy and B 4 C composites.

Table 3 .
Ultimate tensile strength of Al2214 alloy and B 4 C composites.

Table 4 .
Yield strength of Al2214 alloy and B 4 C composites.

Table 5 .
Elongation of Al2214 alloy and B 4 C composites.

Table 6 .
Compression strength of Al2214 alloy and B 4 C composites.