Additive Manufacturing of Metal Matrix Composites PDF

EL Dr. J. Ramkumar PT N Professor Department of Mechanical Engineering and Design IIT Kanpur ▪ Conventional Manufacturing techniques for Metal Matrix Composites ▪ Additive Manufacturing techniques of Metal Matrix Composites E...

EL Dr. J. Ramkumar PT N Professor Department of Mechanical Engineering and Design IIT Kanpur ▪ Conventional Manufacturing techniques for Metal Matrix Composites ▪ Additive Manufacturing techniques of Metal Matrix Composites EL ▪ AM Challenges and Opportunities ▪ Preparation of Composite Materials: Mechanical Mixing ▪ AM of PT ▪ Ferrous Matrix Composites ▪ Titanium-Matrix Composites (TMCs) N ▪ Aluminum Matrix Composite ▪ Nickel Matrix Composites ▪ Factors Affecting Composite Property 1. Liquid-phase methods EL 2. Solid-phase methods 3. Solid/liquid dual-phase methods 4. PT Deposition methods N 1. LIQUID-PHASE METHODS EL i. Mixing liquid metal matrix and ceramic reinforcements ii. Melt infiltration iii. Squeeze casting or pressure infiltration PT iv. Reaction infiltration v. Melt oxidation process N 2. SOLID-PHASE METHODS EL ▪ Powder metallurgy techniques such as pressing followed by sintering I. Forging, and extrusion; PT II. Higher energy and higher rate methods; III. Diffusion bonding; IV. Plastic deformation processes such as friction stir welding and superplastic forming N 3. SOLID/LIQUID DUAL-PHASE METHODS EL ▪ Rheo-casting/Compo-casting ▪ Variable co-deposition of multiphase materials ▪ Spray depositionPT 4. DEPOSITION METHODS ▪ Chemical vapor deposition (CVD) N ▪ Physical vapor deposition (PVD) ▪ Spray forming processes ▪ MMCs are made from metals or alloys strengthened with diverse materials to increase strength, toughness, thermal EL stability, wear resistance, fatigue property, and application- specific qualities. PT ▪ AM's multidirectional and free-form production makes it an attractive manufacturing approach for composites. ▪ The ability to fabricate composites using AM techniques allows for their use in industries that desire lighter, lower-cost N materials, such as automotive, aerospace, and biomedical. General AM methods of MMCs. EL PT N ▪ AM's design freedom allows it to produce novel structures with distinctive geometry. EL ▪ This approach allows producers to insert reinforcing elements into structures to make pieces with the needed qualities. ▪ Laser-processed composite melt has nonequilibrium solidification PT due to rapid heating and cooling on a limited area, which promotes finer structure and consistent distribution of strengthening materials. N ▪ AM can save operation times and costs by manufacturing near-net forms and complicated composites geometry. ▪ AM-fabricated MMC parts are ideal for automotive, aerospace, and other industries. ▪ Most AM techniques allow either particle or fiber-reinforced MMCs. ▪ AM sheet lamination cannot produce complex-shaped MMCs. Challenges and opportunities EL ▪ In heat-based AM processes, the robust Marangoni convection created by increased thermal capillary forces causes liquid metal instability. PT ▪ Gravity, buoyancy, and surface tension affect melt flow. ▪ Then, reinforcements are redistributed. Liquid flow affects their dispersions. N ▪ All over the matrix, filler/reinforcing elements are concentrated around solidification cell borders, creating a honeycomb shape. ▪ Well-distributed high-melting particle fillers can refine grain. Challenges and opportunities EL ▪ According to the composite hypothesis, well-distributed nano- fillers increase nucleation sites and create equiaxed grains, which have weak crystallographic textures. PT ▪ By increasing nucleation, composite columnar structures don't extend over the layer. ▪ Reinforcing element volume affects composite size and shape. N ▪ Based on heat source parameters, reinforcing components can be globular, rod, flower-shaped, cubic, or dendritic. Challenges and opportunities EL ▪ For a laser-based moving heat source, laser power, intensity distribution, spot size, powder feed rate, scanning techniques, and scanning speed will affect the reinforcing elements that PT could be dissolved partly, totally, or remain undissolved throughout the matrix. ▪ Therefore, process input factors affect composite properties and interfacial strength in reinforcing materials and matrix. N Ceramic-reinforced MMCs aren't always preferred. ▪ Porosity,melt pool instability, and post-processing expenditures remain issues. ▪ Variations in physical and mechanical qualities between particles and matrix may cause micro-cracks. Challenges and opportunities EL ▪ Cracks degrade manufactured parts' functionality and cause failure. Ex-situ composites are made by mixing reinforcing ingredients with matrix materials. PT ▪ In these instances, the thermal coefficient mismatch weakens the boundary between the reinforcements and composite matrix. N ▪ Additionally, Ex-situ ceramic filler materials form thin oxide layers on reinforcements' exteriors, reducing bonding strength and causing cracking. ▪ AM composite production can be done through material deposition or a hybrid process, where materials are mixed EL before AM. ▪A blend of matrix-reinforcing elements must have a homogeneous distribution of reinforcing materials for ▪ Mechanical PT consistent bulk composite distribution. mixing/alloying creates metal/alloy-reinforced powders for compression moulding, die casting, extrusion, N remelting, and solidification. Reinforcing element dispersion varies on processing and size. ▪ Mechanical alloying creates finer solid grains by adding particles that increase solid solubility and create a non- equilibrium state. ▪ Grinding improves alloy powder characteristics and chemical compositions. ▪ Type of milling machine, particle size, ball-to-powder ratio, milling speed, and milling time affect particle size and EL characteristics. ▪ Mechanical alloying particle size controls homogeneity PT between two materials. ▪ Time, mechanical energy, and strain hardening affect particle refinement and composite structural uniformity. N ▪ Smaller reinforcing materials allow aggregation with the matrix. ▪ During agglomeration, mechanical connection between particles might infiltrate its lattice and inhibit dislocation motion, increasing material strength. ▪ In mechanical alloying, the rotational speed of the ball mill influences the milling process through the transmission of EL kinetic energy to powder particles from grinding balls during the collision of balls with powders. PT ▪ The kinetic energy Ekin (J) is calculated by (1) N where mb is the mass of the ball (kg) and vc the collision velocity (m/s) ▪ This technique uses a high-erosion mill to enable the process, where higher rotational speed through milling and extended EL impact during alloying results in hardening of the powder particles, thus distorting grain structure PT N Collision between grinding ball and powder particles during mechanical alloying ▪ Cold welding occurs due to extreme plastic deformation during mechanical alloying of ductile powders. EL ▪ To reduce powder agglomeration, lubricants are added to the powder mixture during milling. ▪ Lubricants lower particles' surface tension. PT ▪ In the milling process, the energy E required for particle size reduction is presented as N (2) where γE is the specific surface energy (J/m2 ) and ΔS is the expansion of the surface area (m2 ). ▪ The requirement of lower surface energy emphasizes a shorter milling period and results in finer particles ▪ To understand the impact of the dropping phenomena of powder particles, the kinematic trajectory motion is drawn EL ASSUMPTIONS PT rb is the ball mill radius (m) A is a particle point α is the separating angle (angle N within OA and vertical direction) ω is the rotating speed (rad/s) t0–t5 is the various times in the trajectory (s) ▪ For a particle at point A, the centrifugal force F is equal to the gravitational force in the opposite direction. EL ▪ Therefore, considering the gravity and ignoring the particle friction, F can be presented as PT (3) where mp is the mass of the particles (kg), and g is the gravitational acceleration (m/s2 ) N ▪ Considering the centrifugal force concept, F can be presented as (N) (4) where vp is the velocity of the particle (m/s) ▪ From equations 3 and 4, the rotational speed is EL (5) ▪ The separating angle α, can be calculated as PT (6) N ▪ The aforementioned equations illustrate that the separating angle depends on the rotational speed and radius of the mill and the gravitational acceleration. ▪ The higher separating angle because of greater rotational speed may cause slipping of the particles from the ball mill interior affecting the mixing/alloying process. ▪ Physical and mechanical performance of MMCs is determined by EL ▪ Matrix material qualities ▪ Reinforcing element distribution ▪ Bond strength PT ▪ Production procedures. ▪ MMCs with diverse matrix materials and reinforcements can be made using several AM methods. N ▪ AM processing of MMCs opens new opportunities for multifunctional composites. ▪ The next section presents AM-manufactured ferrous, titanium, aluminum, and nickel matrix composites. ▪ 316 SS-TiC Composite ▪ 316L is a promising austenitic SS to manufacture composites EL because of the ductile matrix property. ▪ Overall, it's a good material for particle reinforcement. ▪ TiC is commonly used with ferrous alloys due to its high melting ▪ stability. PT temperature, reduced density, superior corrosion resistance, increased hardness, thermodynamic properties, and thermal MMC hardness and wear qualities depend on structural restrictions like volume percentage and magnitude of filler materials, N dispersion of inserted elements, and interfacial joining within the matrix and filler material. ▪ If there are no manufacturing faults, more strengthening components increase composites' density, hardness, and elastic modulus. ▪ Solidification Phases of 316 SS-TiC Composite EL ▪ The reaction within Ti and C to form TiC is considered by the higher activation energy. This reaction takes place vigorously because of their exothermic nature. ▪ The possible reaction of TiC formation and the associated variations PT in the enthalpy and Gibbs free energy are thought to communicate with two temperature extents as illustrated as follows (7) N (8) ▪ Solidification Phases of 316 SS-TiC Composite EL (9) PT (10) N (11) The negative value of ΔG in the equation implies a higher chance of TiC formation.  ▪ Solidification Phases of 316 SS-TiC Composite EL ▪ TiC is synthesized in situ from Ti and graphite. ▪ Ti reacts with other materials at high temperatures to generate in- situ strengthening elements. ▪ The formation mechanism of the in-situ 316L-TiC composite is schematically shown below PT N Qian et al., Additive manufacturing of ultrafine-grained austenitic stainless steel matrix composite via vanadium carbide reinforcement addition and selective laser melting: Formation mechanism and strengthening effect, 2019 ▪ TiC reinforcements are found at grain boundaries and inside columnar dendrites in laser-based AM procedures. EL ▪ Higher solidification rates segregate TiC elements, causing this. PT ▪ Strong chaotic fluxes in liquid melt intensify heavy particles in surrounding turbulences. ▪ Chemical inhomogeneity can affect the concentration contour, and structural supercooling can affect the solidification N approach and volume of TiC precipitates. ▪ Small contact time and fast heat transfer can reduce TiC precipitates. ▪ Multiple laser scans over previously melted layers can increase TiC volume due to accumulated heat. ▪ 316 SS-TiB2 Composite EL ▪ In 316–TiB2 composites, reinforcing components form a ring-like structure. ▪ LPBF's faster cooling affects composites. Due to grain advance time, higher cooling rates (106 K/s) limit TiB2 ▪ ▪ PT grain growth. This makes finer TiB2 particles. The laser AM process's temperature gradient causes a melt's surface tension gradient. N ▪ This gradient adds Marangoni convection to move TiB2 particles by limiting accumulation and regulating distribution across the cemented matrix. ▪ 316 melts entirely, but TiB2 doesn't. Marangoni forces move TiB2- elements. ▪ Matrix melting repels TiB2 particles. Repulsive force and Marangoni convection generate a TiB2 ring-like structure. ▪ H13–TiB2 Composite EL ▪ Laser AM in tool production allows for the digital production of intricately formed parts. ▪ AM reduces the cost of tools, shortens production time, and reduces personnel through robotics. ▪ ▪ PT Laser-processed H13–TiB2 has -Fe and TiB2 phases, but no austenite. These structures may affect laser melting's Gaussian heat distribution. N ▪ Faster heating and solidifying cycles stimulate fine equiaxed grains with uniform TiB2 reinforcement along H13 grain borders. ▪ During laser melting, when a full liquid forms, the dissolution mechanism generates strengthening phases by heterogeneous TiB2 nucleation and grain growth. ▪ H13–TiC Composite EL ▪ The laser's faster heating and cooling cycle helps TiC structures happen by shortening the amount of time TiC grains need to grow. ▪ When the temperature goes up, the Marangoni flow gets stronger, and capillary forces push the liquid along. PT ▪ So, the shear and rotational forces that form around the TiC particles could be a driving force for the particles to spread out evenly, which stops them from sticking together. N ▪ Also, when the volumetric energy density is lower, the torque is less, which makes particles stick together more. ▪ Ferrous–WC Composite EL ▪ AM ceramic arenas are interested in MMCs strengthened with ceramic particles. ▪ Ceramic-reinforced ferrous composites perform better. WC has a high melting temperature and excellent wettability with ▪ ▪ ▪ PT many ferrous alloys. WC can maintain 1400 C room temperature hardness. Choosing the right reinforcing materials and matrix is key to N boosting wear resistance, therefore the interface is important. ▪ Fe-based alloys are reinforced with ceramic components to improve wear property.  ▪ Ferrous–WC Composite ▪ In Fe–WC composite, dissolved WC EL reinforcing components release W and C in the liquid melt. ▪ W and C atoms react with ferrous alloy to generate carbides near grain ▪ boundaries. PT The gradient interface MC3 (M = W, Fe, Cr, Ni) develops between WC reinforcing element and matrix during laser AM N procedures. ▪ Gradient interfaces may strengthen WC and Fematrix bonds. ▪ Size and shape of the interface gradient Microstructure showing the fluctuate with laser power, intensity, and morphology of matrix, interface, spot size. and WC reinforcement in MMC. Gu et al. Laser additive manufactured WC reinforced Fe-based composites with gradient reinforcement/matrix interface and enhanced performance, Compos. Struct. 2018 ▪ Ferrous–WC Composite EL ▪ Fe–WC composite performance involves densification, gradient interface, microstructural morphology, and hardness development. ▪ First, when densification is low at a high scanning speed, the material can be lost from the matrix due to pores. ▪ ▪ improves wear. PT Lower scan speed might result in increased densification, which Second, the in-situ reaction's gradient interface improves wear. N ▪ A weak interfacial connection between reinforcing components and matrix is caused by composite wear. ▪ Ferrous–WC Composite EL ▪ Interfacial layers without pores and fissures ensure composite bonding. ▪ Thicker interfacial layers provide strong bonding, making it difficult to wear away WC components during the application, improving wear property. PT ▪ Higher composite hardness can hinder adhesive processes like scuffing and removing material, reducing wear rate, and improving wear property. N ▪ Ferrous–VC Composites EL ▪ Through LPBF, vanadium carbides reinforce ferrous matrix composites. ▪ In this process, the laser's energy and the pressure/flow in the laser- stimulated liquid melt pool disintegrate micron-sized VC through a ▪ PT melting-solidifying mechanism. The laser light quickly heats the 316L/VC mixture, forming a molten region of entirely dissolved V8C7/316L liquids. N ▪ V8C7 can quickly dissolve and release V and C due to tiny particle size, high surface tension, and laser heat. ▪ The tiny pressure on ultrafine VC in the liquid melt pool accelerates the rapid melt process.  ▪ Ferrous–VC Composites Schematic diagram shows that EL the formation mechanism of ferrous matrix composites strengthens with VC in LPBF technique PT N Qian et al., Additive manufacturing of ultrafine-grained austenitic stainless steel matrix composite via vanadium carbide reinforcement addition and selective laser melting: Formation mechanism and strengthening effect, 2019 ▪ Ferrous–VC Composites EL ▪ After the laser source leaves the melt, it solidifies quickly. ▪ During fast solidification, VC and VCx develop through heterogeneous nucleation and grain expansion of VC nuclei. The matured VCx strengthening components will be disseminated ▪ ▪ progression. PT at grain boundaries and in austenite grains due to nucleation and When VCx phases become bulky, grain expansion pushes them N toward grain boundaries. ▪ VCx phases are retained within austenite grains. ▪ As laser AM has a quick solidification process, few V and C diffuse into austenite solid solution. ▪ Ti–TiC Composite EL ▪ In laser-based additive manufacturing (AM) of Ti–TiC composites, different amounts of Ti and TiC powders are mixed and milled with a ball mill to get a better density. ▪ TiC elements are made by laser AM through dissolution or PT precipitation mechanisms, such as heterogeneous nucleation of TiC and the growth of grains. ▪ The ex-situ construction of Ti-TiC and the distribution of TiC reinforcement depend on the processing conditions, such as the N functional energy density. ▪ At higher energy densities, the TiC reinforcing element spreads out in the form of a network array with a dendritic shape. ▪ Ti–TiC Composite EL ▪ At lower energy densities, the TiC gets smaller and spreads out more evenly. ▪ The lower energy density can also change the shape of TiC from rougher dendritic to whisker-like to lamellar. PT ▪ Higher scanning speeds cause faster cooling rates, which means there isn't enough time for TiC to grow in the composites. ▪ This leads to changes and improvements in the microstructure. N ▪ Ti–TiB Composites ▪ Even though a lot of different particles can be used to reinforce EL TMCs, ceramic particles like TiB and TiC have gotten a lot of attention because they have a good chemical affinity with the matrix. This makes it easier for the matrix and particles to stick together ▪ ▪ PT and makes the interfaces more complete. TiB is a steady element, even with a very small solubility of boron in titanium (