Effects of Zr,Ti and Sc additions on the microstructure and mechanical properties of Al-0.4Cu-0.14Si-0.05Mg-0.2Fe alloys

The evolution of microstructure and mechanical properties of Al-0.4Cu-0.14Si-0.05Mg-0.2Fe (wt.%) alloys, micro-alloyed with Zr, Ti and Sc, were investigated. The addition of 0.2%Zr to base alloy accelerates the precipitation of Si-rich nano-phase in α-Al matrix, which plays an important role in improving the mechanical properties of an alloy. The tensile strength increases from 102 MPa for the base alloy to 113 MPa for the Zr-modified alloy. Adding 0.2%Zr + 0.2%Ti to base alloy effectively refines α-Al grain size and accelerates the precipitation of Si and Cu elements, leading to heavy segregation at grain boundary. By further adding 0.2%Sc to Zr + Ti modified alloy, the segregation of Si and Cu elements is suppressed and more Si and Cu precipitates appeared in α-Al matrix. Accompanied with the formation of coherent Al₃Sc phase, the tensile strength increases from 108 MPa for the Zr + Ti modified alloy to 152 MPa for the Sc-modified alloy. Due to excellent thermal stability of Al₃Sc phase, the Sc-modified alloy exhibits obvious precipitation hardening behavior at 350 °C, and the tensile strength increases to 203 MPa after holding at 350 °C for 200 h.     

Deposition of Phase-pure Cr2AlC Coating by DC Magnetron Sputtering and Post Annealing Using Cr-Al-C Targets with Controlled Elemental Composition but Different Phase Compositions

Polycrystalline Cr_2AlC coatings were prepared on M38G superalloy using a two-step method consisting of magnetron sputtering from Cr-Al-C composite targets at room temperature and subsequent annealing at 620°C. Particularly, various targets synthesized by hot pressing mixture of Cr, Al, and C powders at 650–1000°C were used. It was found that regardless of the phase compositions and density of the composite targets, when the molar ratio of Cr:Al:C in the starting materials was 2:1:1, phase-pure crystalline Cr_2AlC coatings were prepared by magnetron sputtering and post crystallization. The Cr_2AlC coatings were dense and crack-free and had a duplex structure. The adhesion strength of the coating deposited on M38G superalloy from the 800°C hot-pressed target and then annealed at 620°C for 20 h in Ar exceeded82 ± 6 MPa, while its hardness was 12 ± 3 GPa.     

Microstructure and brazing mechanism of porous Si3N4/Invar joint brazed with Ag-Cu-Ti/Cu/Ag-Cu multi-layered filler

Porous Si_3N_4 was brazed to Invar alloy in this study, and Ag-Cu-Ti/Cu/Ag-Cu multi-layered filler was designed to inhibit the formation of Fe_2Ti and Ni_3Ti intermetallic compounds. The effects of the brazing temperature and the thickness of Cu interlayer on the microstructure and mechanical properties of brazed joints were investigated. The typical microstructure of the joint brazed with multi-layered filler was porous Si_3N_4/TiN + Ti_5Si_3/Ag-Cu eutectic/Cu/Ag-Cu eutectic/Cu-rich layer + diffusion layer/Invar. When the brazing temperature increased, the reaction layer at the ceramic/filler interface grew thicker and the Cu interlayer turned thinner. As the thickness of Cu interlayer increased from 50 to 150μm, the joint strength first increased and then decreased. In this research, the maximum shear strength(73 MPa) was obtained when being brazed at 1173 K with a 100μm Cu interlayer applied in the filler, which was 55% higher than that brazed with single Ag-Cu-Ti brazing alloy and had reached 86% of the ceramic. The release of residual stress and the barrier effect of Cu interlayer to inhibit the formation of Fe_2Ti and Ni_3Ti intermetallics played the major role in the improvement of joint strength.     

In-situ synthesis of TiC/Fe alloy composites with high strength and hardness by reactive sintering

Fe alloy composites reinforced with in-situ titanium carbide(Ti C) particles were fabricated by reactive sintering using different reactant C/Ti ratios of 0.8,0.9,1 and 1.1 to investigate the microstructure and mechanical properties of in-situ Ti C/Fe alloy composites.The microstructure showed that the in-situ synthesized Ti C particles were spherical with a size of 1–3 μm,irrespective of C/Ti ratio.The stoichiometry of in-situ Ti C increased from 0.85 to 0.88 with increasing C/Ti ratio from 0.8 to 0.9,but remained almost unchanged for C/Ti ratios between 0.9 and 1.1 due to the same driving force for carbon diffusion in Ti Cxat the common sintering temperature.The in-situ Ti C/Fe alloy composite with C/Ti = 0.9 showed improved mechanical properties compared with other C/Ti ratios because the presence of excess carbon(C/Ti = 1 and 1.1) resulted in unreacted carbon within the Fe alloy matrix,while insufficient carbon(C/Ti = 0.8)caused the depletion of carbon from the Fe alloy matrix,leading to a significant decrease in hardness.This study presents that the maximized hardness and superior strength of in-situ Ti C/Fe alloy composites can be achieved by microstructure control and stoichiometric analysis of the in-situ synthesized Ti C particles,while maintaining the ductility of the composites,compared to those of the unreinforced Fe alloy.Therefore,we anticipate that the in-situ synthesized Ti C/Fe alloy composites with enhanced mechanical properties have great potential in cutting tool,mold and roller material applications.     

Effects of high temperature treatment on microstructure and mechanical properties of laser-clad NiCrBSi/WC coatings on titanium alloy substrate

Laser-clad composite coatings on the Ti6Al4V substrate were heat-treated at 700, 800, and 900 °C for 1 h. The effects of post-heat treatment on the microstructure, microhardness, and fracture toughness of the coatings were investigated by scanning electron microscopy, X-ray diffractometry, energy dispersive spectroscopy, and optical microscopy. The wear resistance of the coatings was evaluated under dry reciprocating sliding friction at room temperature. The coatings mainly comprised some coarse gray blocky (W,Ti)C particles accompanied by the fine white WC particles, a large number of black TiC cellular/dendrites, and the matrix composed of NiTi and Ni₃Ti; some unknown rich Ni- and Ti-rich particles with sizes ranging from 10 nm to 50 nm were precipitated and uniformly distributed in the Ni₃Ti phase to form a thin granular layer after heat treatment at 700 °C. The granular layer spread from the edge toward the center of the Ni₃Ti phase with increasing temperature. A large number of fine equiaxed Cr₂₃C₆ particles with 0.2–0.5 μm sizes were observed around the edges of the NiTi supersaturated solid solution when the temperature was further increased to 900 °C. The microhardness and fracture toughness of the coatings were improved with increased temperature due to the dispersion-strengthening effect of the precipitates. Dominant wear mechanisms for all the coatings included abrasive and delamination wear. The post-heat treatment not only reduced wear volume and friction coefficient, but also decreased cracking susceptibility during sliding friction. Comparatively speaking, the heat-treated coating at 900 °C presented the most excellent wear resistance.     

Reaction mechanisms,resultant microstructures and tensile properties of Al-based composites fabricated in situ from Al-SiO2-Mg system

Reaction mechanisms, microstructures and tensile properties of the aluminum matrix composites made from Al-SiO₂-Mg system were investigated. When the temperature increased from room temperature to around 761 K, Mg dissolved into Al to form Mg-Al alloy. As the temperature increased to about 850 K, the remaining Mg reacted with SiO₂ to form MgO, Mg₂Si and Si as expressed in step reaction I: 6Mg + 2SiO₂ → 4MgO + Mg₂Si + Si. Finally, with a further increase in temperature, the remaining SiO₂ reacted with Al to produce Al₂O₃ and Si, while MgO reacted with Al₂O₃ to form MgAl₂O₄ as expressed in step reaction II: 4Al + 3SiO₂ + 2MgO → 2MgAl₂O₄ + 3Si. The Si also dissolved into matrix Al to form Al-Si alloy. Accordingly, its reaction process consisted of two steps and their apparent activation energies were 218 kJ/mol and 192 kJ/mol, respectively. As compared to the composites prepared by Al-SiO₂ system, its density increased from 2.4 to 2.6 g/cm³, and its tensile strength and elongation increased from 165 MPa and 3.95% to 187 MPa and 7.18%, respectively.     

Investigation of wear behaviours of Al matrix composites reinforced with different B4C rate produced by powder metallurgy method

In this study, the effects of wear behaviours of Al matrix composites reinforced with different B₄C rate produced by powder metallurgy method were investigated. Al and B₄C powders with purity of 99.9% and sizes of 25–44 µm were prepared as pure Al, 4% B₄C/Al, 8% B₄C/Al, 12% B₄C/Al and 16% B₄C/Al. After these prepared mixtures were pressed under 350 MPa, they were sintered for 90 min at 580 °C in atmospheric environment. Microhardness and wear tests of the produced samples were carried out. Wear experiments of these composites were performed with specially manufactured test equipment at different application loads (5 N, 10 N and 15 N), different sliding distances (250 m, 500 m, 750 m and 1000 m) and a constant speed of 0.46 m/s. In addition, optical microscope, SEM, EDS analyses were used to determine the microstructural changes in the worn and unworn surface of the manufactured composite materials. The results of experimental studies show that the increasing the B₄C reinforced rate in composites with Al matrix has led to increase of the hardness and to reduce of the wear loss.     

The effect of fabrication processes on the mechanical and interfacial properties of SiCf/Cu–matrix composites

Three groups of SiC_f/Ti/Cu composites were prepared under conditions of 650 °C + 105 min (sample 1#), 750 °C + 85 min (sample 2#) and 840 °C + 50 min (sample 3#), respectively, by foil-fiber-foil method (FFF), and their room temperature tensile strengths were established. The aim is to model the reactive bonding states between Ti and SiC fiber and between Ti and Cu when Ti is used as interfacial adhesion promoters in SiC_f/Cu–matrix composites. The fracture surfaces, SiC_f/Ti interfaces and Ti/Cu interfaces were investigated by scanning electron microscopy (SEM), optical microscopy and energy dispersive spectroscopy (EDS). The tensile tests show that the tensile strengths of samples 1# and 2# are not obviously enhanced due to the weak bonding strength between SiC fiber and Ti, while those of sample 3# are achieved above 90% of ROM (the rule of mixtures) strength because of excellent bonding between SiC fiber and Ti. However, there are distinct Ti/Cu interfacial reaction zones after the three processes, which are approximately 5.4, 9.0 and 13.3 μm thick, respectively. The Ti/Cu interfacial reaction products are mainly distributed in four layers. In samples 1# and 2#, the products are predicted to be Cu₄Ti, Cu₃Ti₂, CuTi and CuTi₂ according to their chemical compositions determined by EDS, while in sample 3#, the products are Cu₄Ti, Cu₄Ti₃, CuTi and CuTi₂. Additionally, the relationships between the thickness of Ti interlayer and its reaction with C and Cu are also discussed, and an optimal thickness of Ti is introduced.     

Influence of TiBw volume fraction on microstructure and high-temperature properties of in situ TiBw/Ti6Al4V composites with TiBw columnar reinforced structure fabricated by pre-sintering and canned extrusion

Tailoring TiBw volume fraction was utilized in TiBw/Ti6Al4V composites to pursue performance optimization for potential high-temperature applications. Detailed investigations focused on the influence of TiBw volume fraction on microstructure and its correlations with mechanical properties mainly at high temperatures ranging from 500 °C to 700 °C. Highly aligned TiB whiskers along extrusion direction caused the formation of TiBw columnar reinforced structure, which was composed of ductile TiBw-poor interior regions and hardened TiBw-rich boundaries. Refined prior β phases arising from dynamic recrystallization led to the size reduction in α colonies. This tendency commonly accompanied with the formation of equiaxed α phase was evidently enhanced by the restriction of increasing TiB whiskers at the boundaries. Much better strengthening of TiB whiskers was achieved on the premise of good interfacial bonding with Ti matrix at high temperatures, and the strengthening depended linearly on their volume fractions, with strength increments of about 44.3 MPa/vol.% at 500 °C, and 27.5 MPa/vol.% at 600 °C, yet merely 6.3 MPa/vol.% at 700 °C. Attributed to the softening of Ti matrix and the crack retardation of ductile TiBw-poor regions by raising temperature, enhanced ductility was negatively correlated with TiBw volume fraction below 600 °C, but positively at 700 °C under the possible grain boundary sliding inspired by ample equiaxed α phase.     

Synergistic effect of organic and inorganic nano fillers on the dielectric and mechanical properties of epoxy composites

Titanium oxide TiO₂/epoxy and TiO₂ with detonation nano-diamond (DND)/epoxy nanocomposites were prepared by using ultrasonication method. TiO₂ and DND particles as reinforcement species and epoxy as matrix were used to produce nanocomposites. The addition of DND particles into TiO₂/epoxy composite improved the dielectric and mechanical properties of nanocomposites in significant amount. The dielectric properties of TiO₂-DND/epoxy nanocomposite demonstrated increase in permittivity and conductivity after addition of the DND particles. The maximum and minimum reflection losses of TiO₂-DND/epoxy nanocomposite for 0.6 and 0.2 wt% DND loading were detected at ?14.5 and ?1.3 dB, respectively. The flexural and tensile strength of TiO₂-DND/epoxy nanocomposites with the addition of 0.4 wt% DNDs were enhanced to 220% and 223%, respectively. Additionally, the energy to break and percent break strain were 3.9 J and 3.86, respectively for 0.4 wt% DND loading in TiO₂-DND/epoxy nanocomposite. Therefore, the present work findings claim that DND particles are well suitable to enrich the dispersion of TiO₂ nanoparticles in epoxy matrix, which develops a strong load transfer interface between the nanoparticles and epoxy matrix and consequently leads to superior properties.     

New ductile laminate structure of Ti-alloy/Ti-based metallic glass composite with high specific strength

Bulk laminate structure of Ti-alloy/Ti-based metallic glass composite(MGC) was prepared by melting a preform of alternate stack-up foils in the high vacuum atmosphere. The composite demonstrates a good combination of yield strength(~1618 MPa), plasticity(~4.3%) and specific fracture strength(384 × 10~3 Nmkg~(-1)) in compression. The maintained yield strength results from the unique microstructure composed of the Ti layer, the solution layer with gradient structure and the MGC layer. Such a multilayer structure effectively inhibits the propagation of shear band, leading to the enhanced plasticity. Those extraordinary properities suggest that combining ductile lamella with brittle metallic glass(MG) by such a lay-up method can be an effective way to improve mechanical properties of MG.     

Development of high mechanical properties and moderate thermal conductivity cast Mg alloy with multiple RE via heat treatment

A new cast Mg–2 Gd–2 Nd–2 Y–1 Ho–1 Er–0.5 Zn–0.4 Zr(wt%) alloy was prepared by direct-chill semicontinuous casting technology. The microstructure, mechanical properties and thermal conductivity of the alloy in as-cast, solid-solution treated and especially peak-aged conditions were investigated. The as-cast alloy mainly consists of β-Mg matrix,(Mg, Zn)_3 RE phase and basal plane stacking faults. After proper solid-solution treatment, the microstructure becomes almost Mg-based single phase solid solution except just very few RE-riched particles. The as-cast and solid-solution treated alloys exhibit moderate tensile properties and thermal conductivity. It is noteworthy that the Mg alloy with 8 wt% multiple RE exhibits remarkable age-hardening response( HV = 35.7), which demonstrates that the multiple RE(RE = Gd, Nd, Y, Ho, Er) alloying instead of single Gd can effectively improve the age-hardening response.The peak-aged alloy has a relatively good combination of high strength/hardness(UTS(ultimate tensile strength) 300 MPa; TYS(tensile yield strength) 210 MPa; 115.3 HV), proper ductility(ε≈ 6%) and moderate thermal conductivity(52.5 W/(m K)). The relative mechanisms mainly involving aging precipitation of β￠ and β' phases were discussed. The results provide a basis for development of high performance cast Mg alloys.     

Effect of TiB2 content on the characteristics of spark plasma sintered Ti–TiBw composites

Spark plasma sintering (SPS) was employed to fabricate monolithic titanium and in-situ formed TiB whisker (TiB_w) reinforced titanium matrix composites (TMCs) by adding different amounts of TiB₂ as boron source. The sintering process was completed at 1050 °C for 5 min under 50 MPa. The influences of TiB₂ content (0.6–9.6 wt. %) on microstructural evolution and mechanical properties of TMCs were investigated. Thermodynamics, XRD analysis and microstructural investigations confirmed the in-situ formation of TiB_w in the composite samples. However, some semi-reacted TiB₂ phases, surrounded by TiB coronas, were remained in the microstructure due to the unfinished chemical reaction between the components during a short-time sintering process. The results showed that all samples were appropriately densified by SPS process into the almost dense parts with relative density no less than 97.5%. While bending strength decreased and hardness increased with increasing TiB₂ content, the sample with 4.8 wt. % TiB₂ had the maximum tensile strength. Fractographical assessments showed that the addition of TiB₂ hindered the grain growth of titanium matrix. With increasing TiB₂ content, fracture mode changed from a multiple pattern to a predominantly transgranular and brittle state.     

Influence of size and distribution of W phase on strength and ductility of high strength Mg-5.1Zn-3.2Y-0.4Zr-0.4Ca alloy processed by indirect extrusion

A high strength Mg-5.1Zn-3.2Y-0.4Zr-0.4Ca(wt%) alloy containing W phase(Mg_3Y_2Zn_3) prepared by permanent mold direct-chill casting is indirectly extruded at 350?C and 400?C, respectively. The extruded alloys show bimodal grain structure consisting of fine dynamic recrystallized(DRXed) grains and unrecrystallized coarse regions containing fine W phase and β2' precipitates. The fragmented W phase particles induced by extrusion stimulate nucleation of DRXed grains, leading to the formation of fine DRXed grains, which are mainly distributed near the W particle bands along the extrusion direction. The alloy extruded at 350?C exhibits yield strength of 373 MPa, ultimate tensile strength of 403 MPa and elongation to failure of 5.1%. While the alloy extruded at 400?C shows lower yield strength of 332 MPa,ultimate tensile strength of 352 MPa and higher elongation to failure of 12%. The mechanical properties of the as-extruded alloys vary with the distribution and size of W phase. A higher fraction of DRXed grains is obtained due to the homogeneous distribution of micron-scale broken W phase particles in the alloy extruded at 400?C, which can lead to higher ductility. In addition, the nano-scale dynamic W phase precipitates distributed in the un DRXed regions are refined at lower extrusion temperature. The smaller size of nano-scale W phase precipitates leads to a higher fraction of un DRXed regions which contributes to higher strength of the alloy extruded at 350?C.     

Microstructure and corrosion behavior of Ti nanoparticles reinforced Ni–Ti composite coatings by electrodeposition

A survey on electrochemical codeposition of Ti nanoparticles in Ni matrix coating is given. The influences of Ti nanoparticle loadings in electrolyte on the microstructure, microhardness and corrosion behavior of Ni–Ti coatings were investigated. The results showed that a pyramidal surface structure evolved into a spherical surface structure of the coatings with increasing Ti nanoparticle loading. The content of Ti in the Ni–Ti coatings first increased and reached the maximum value of 7.1 vol.% at the loading of 16 g/L, then decreased due to agglomeration of nanoparticles. The [2 0 0] preferred orientation gradually evolved to [1 1 1] orientation with increasing Ti nanoparticle loading. At Ti nanoparticle loading of 16 g/L, the minimum crystallite size (44 nm) and maximum microstrain (0.25%) were obtained. The microhardness of the Ni–Ti coatings was improved and obtained the maximum value at the loading of 16 g/L. The anti-corrosion behavior of the Ni–Ti coatings had increased trend with increasing Ti nanoparticle loading. The pitting corrosion and the selective dissolution of Ti nanoparticles happened in corrosion of Ni–Ti coating electrodeposited at the loading of 16 g/L in a 3.5 wt.% NaCl solution.     

Powder metallurgy titanium metal matrix composites reinforced with carbon nanotubes and graphite

Carbon nanotubes (VGCF) and graphite (Gr) reinforced Ti metal matrix composites (TiMMCs) were prepared via powder metallurgy. 0–0.4 wt% VGCF/Gr and Ti mixture powders were prepared by rocking mill. The as-premixed powders were consolidated at 1073 K using spark plasma sintering (SPS). Hot extrusion was performed at 1273 K with an extrusion ratio of 37:1. Microstructures and mechanical properties of the as-extruded Ti composites were investigated to evaluate strengthening effects of VGCF/Gr on Ti matrix. Mechanical strength of Ti–VGCF/Gr composites was augmented when VGCF/Gr contents were increased from 0.1 to 0.4 wt%. Yield strength (YS) and ultimate tensile strength (UTS) of Ti-0.4 wt% VGCF composites were increased 40.4% and 11.4% as compared to pure Ti, while those values were 30.5% and 2.1% for Ti–0.4 wt% Gr. The strengthening mechanism including grain refinement, carbon solid solution strengthening and TiC/carbon dispersion strengthening was discussed in detail.     

Microstructure characterization,mechanical properties,compressibility and sintering behavior of Al-B4C nanocomposite powders

In the present work, Al-xB₄C nanocomposite (x = 0, 1, 2, 3, 4 and 5 in wt%, having the average B₄C size of 50 nm) were prepared using a high-energy ball mill. The milling times up to 16 h were applied. Then, the microstructural evolutions, mechanical properties, compressibility and sintering behavior of nanocomposites were investigated. The changes in powders morphology and microstructure during the milling process were characterized by laser diffraction particle size analyzer (LDA), SEM, XRD, EDS and TEM techniques. Compressibility and sintering behavior of milled powders compacted under different pressures (100–900 MPa) and at different sintering temperatures (500, 550 and 600 °C) were also studied. The pressing behavior of the nanocomposites was analyzed using linear compaction equations developed by Heckel, Panelli-Filho and Ge. The results showed the significant effects of B₄C amounts and sintering temperatures on the compressibility and sintering behavior of nanocomposites. The increase in the B₄C amount led to a decrease in both the compressibility rate and the sinterability of specimens. The maximum compression strength of 265 MPa and Vickers hardness of 165 VHN were obtained for Al-5 wt.% B₄C nanocomposite milled for 16 h followed by sintering at 600 °C.     

Nanocomposite protective coatings based on Ti–N–Cr/Ni–Cr–B–Si–Fe,their structure and properties

The first results of manufacturing and investigations of a new type of nanocomposite protective coatings are presented. They were manufactured using a combination of two technologies: plasma-detonation coating deposition with the help of plasma jets and thin coating vacuum-arc deposition. We investigated structure, morphology, physical and mechanical properties of the coatings of 80–90 μm thickness, as well as defined the hardness, elastic Young modulus and their corrosion resistance in different media. Grain dimensions of the nanocomposite coatings on Ti–N–Cr base varied from 2.8 to 4 nm. The following phases and compounds formed as a result of plasma interaction with the thick coating surface were found in the coatings: Ti–N–Cr (200), (220), γ-Ni₃–Fe, a hexagonal Cr₂–Ti, Fe₃–Ni, (Fe, Ni)N and the following Ti–Ni compounds: Ti₂Ni, Ni₃Ti, Ni₄Ti, etc. We also found that the nanocomposite coating microhardness increased to H = 31.6 ± 1.1 GPa. The Young elastic modulus was determined to be E = 319 ± 27 GPa – it was derived from the loading–unloading curves. The protective coating demonstrated the increased corrosion resistance in acidic and alkaline media in comparison with that of the stainless steel substrate.     

Wear behaviors of Fe-based amorphous composite coatings reinforced by Al2O3 particles in air and in NaCl solution

In this paper, the influence of the addition of Al₂O₃ particles on the microstructure and wear properties of Fe-based amorphous coatings prepared by high velocity oxygen fuel (HVOF) has been studied. The wear behaviors of the composite coatings were evaluated against Si₃N₄ in a pin-on-disk mode in air and in 3.5 wt.% NaCl solution. It was found that the Al₂O₃ particles were homogenously distributed in the amorphous matrix and the composite coatings exhibited improved wear resistance and reduced coefficient of friction (COF) in both air and wet conditions as compared to the monolithic amorphous coating. The composite coating reinforced with 20 wt.% Al₂O₃ particles exhibit the best wear performance, which, for example, has extremely low COF (< 0.2) and high wear resistance (2–3 times higher than monolithic amorphous coating). Detailed analysis on the worn surface indicated that the wear mechanism for the amorphous and composite coatings is similar and is dominated by oxidative delamination in air and by corrosion wear in 3.5% NaCl solution. The enhanced wear resistance is mainly attributed to the addition of Al₂O₃ particles which exhibit high hardness, good corrosion resistance and excellent chemical and thermal stability.     

Preparation of Al matrix nanocomposites by diluting the composite granules containing nano-SiCp under ultrasonic vibaration

In this work, an efficient process by diluting the nano-SiCp/Al composite granules in the molten matrix under ultrasonic vibration(UV) was developed to prepare metal matrix nano-composites(MMNCs).Millimeter-sized composite granules with high content of SiC particle(8 wt%) were specially fabricated by dry high-energy ball milling(HBM) without process control agent, and then remelted and diluted in molten Al alloy under UV. The MMNCs melt was finally squeeze cast under a squeeze pressure of 200 MPa, Microstructure of the composite granules during dry HBM was investigated, and the effect of UV on microstructure and mechanical properties of the MMNCs was discussed. The results indicate that nano-SiC particles are uniformly distributed in the nano-SiCp/Al composite granules, which are covered by vestures of pure Al. During diluting, nano-SiC particles released from the composite granules are quickly dispersed in the molten matrix by UV within 4 min. Microstructure of MMNCs is significantly refined under UV and squeeze casting, eutectic Si phase modified to fine islands with an average length of 1.4 μm. Tensile strength of the squeeze cast MMNCs with 1 wt% of nano-SiC particles is 269 MPa, which is improved by 25% compared with the A356 alloy matrix.