Refinement Strengthening Research Articles

Formation process, microstructure, and mechanical properties of an ultrafine dual-phase alloy formed through phase transition of 18R-type long-period stacking ordered in Mg85Zn6Y9 under high pressure

The 18R-type long-period stacking ordered (LPSO) structure in Mg85Zn6Y9 exhibits phase transition into D03 and α-Mg (D03/α-Mg) before it transforms into a liquid phase with the increase in temperature at 7.8 GPa. First-principles calculations suggest that the energy barrier between 18R-type LPSO and D03/α-Mg decreases with pressure. A further increase in the temperature decreases the energy difference between LPSO and D03/α-Mg. Therefore, the free energy variations due to the effects of both pressure and temperature cause phase transition. The D03/α-Mg phases formed at high pressure can be recovered at 0.1 MPa and room temperature. The phase transition from 18R-type LPSO structure to D03/α-Mg causes inner-grain diffusion and generates a lamellar structure. The thickness of the lamellar structure decreases with the increasing pressure until it reaches 65 nm at 15 GPa. Moreover, the alloy solidified above 5 GPa also comprises D03/α-Mg phases. The alloy solidified at 5 GPa exhibits a typical eutectic lamellar structure. However, spherulite-like polycrystalline microstructures containing ultrafine grains are obtained when the alloys are solidified at 10 and 15 GPa. The microstructure variations are caused by an increase in the degree of supercooling due to atomic diffusion suppression with the increasing pressure. The alloys containing D03/α-Mg exhibit both low modulus and ultrahigh strength. The Young’s modulus is related to the presence of the D03 and α-Mg phases in the alloy structure. In contrast, the increase in σy can be attributed to the grain refinement strengthening.

Characterization and strengthening mechanism of high-strength medium carbon spring steels

To develop higher strength spring steels with better performance for advanced automotive and transportation industries in line with the trend of lightweight, the strengthening mechanism of two practical 55SiCr and 55SiCrNbV spring steels, which represents plain and micro alloyed spring steels, has been investigated based on the systematic characterization of microstructures, hardness, and tensile test. The tensile strength and hardness were found to be correlated well in a linear relationship. Then the strengthening coefficients of C, Si, Cr and Mn were determined to quantify the solid solution strengthening. The strengthening mechanism of spring steels was found to be the summation of solid solution strengthening, grain refinement, dislocation, and precipitation strengthening, which agree well with the tensile test results. The strengthening mechanism could be used as guidance to develop next generation spring steels, which well explained the ultra-high strength spring steels over 2200 MPa class in the literature.

Effect of B4C on microstructure evolution and high-temperature mechanical properties of TiAl matrix composites

This study synthesized and characterized the Ti-48Al-2Cr-2 Nb-based composite reinforced by B4C addition, which was produced by spark plasma sintering. The grain size of composites decreased significantly from 225 ± 5 µm to 51 ± 5 µm with the increase of B4C content, mainly due to the pinning effect of in-situ generated TiB2 and Ti2AlC particles at grain boundaries, which limited the rapid grain growth of the matrix. With the addition of B4C, the volume fraction of Ti2AlC increased from 3.0% to 7.4%, with an average size of approximately 5 µm. The ultimate tensile strength and total fracture elongation of the Ti-48Al-2Cr-2 Nb alloy were 482.9 MPa and 10.2% at 800 ℃, correspondingly. With 0.3 wt% addition of B4C, B4C/Ti-48Al-2Cr-2 Nb composite exhibited superior strength (579.5 MPa) and ductility (12.6%) at the same tensile temperature. The reinforced strength of the composite was mainly attributed to the grain refinement and precipitation strengthening.

Sintering, microstructure, and mechanical properties of ZrO2-doped Al2O3

ABSTRACT In the present work, the effect of Zr-doping on the sintering, microstructure development, and mechanical properties of polycrystalline Al2O3 was studied. Dopant concentrations of 830 and 2070ppm cationic ratio of Zr in Al2O3 corresponding to 2000 and 5000 wt. ppm of ZrO2 in Al2O3, respectively, were used. The sintering schedule of undoped as well as Zr-doped Al2O3 samples was optimised following a series of precoarsening experiments. The Zr-doped Al2O3 ceramics exhibited controlled grain size and improved density. Upon increasing the Zr-dopant concentration from 830 cat. ppm to 2070 cat. ppm. Zr-doped Al2O3 ceramics having a refined microstructure with a homogeneous distribution of controllably grown ZrO2 in Al2O3 matrix was obtained. Microhardness of the Zr-doped samples showed negligible dependence with Zr-doping, whereas mechanical strength was found to improve with it. The improvement in strength was attributed to the combined effect of improved sinter density, microstructural refinement, and grain-boundary strengthening.

Microstructure evolution and strengthening mechanism of air-hardening steel subjected to the austenitizing annealing treatment

The microstructure evolution and mechanical properties of air-hardening steel subjected to different austenitizing annealing treatments were investigated in this study and, especially, the precipitation behavior of the steel was analyzed, as well as the strengthening mechanism of the steel was elucidated on the basis of systematic microstructural characterization. Results reveal that a ferrite + martensite dual-phase structure with about 700 MPa tensile strength and 20% elongation can be obtained by austenitizing the experimental steel in the range of 750∼800 °C; while austenitizing between 850 °C and 950 °C results in granular bainite + lath bainite with about 950 MPa tensile strength and 12% elongation. The experimental steel has the highest strength after austenitizing at 900 °C with lots of nano-scale (Ti, Mo, V)C particles distributed in its matrix. Quantitative calculation results illustrate that the main strengthening factors are grain refinement strengthening, dislocation strengthening and precipitation strengthening. In addition, due to the potential interaction effect between different strengthening factors, a modified strengthening model is proposed to describe the strengthening behavior of the air-hardening steel when it is heat-treated in the two-phase region.

Nitrogen‐Enhanced Temperature Dependence of Grain Refinement Strengthening in Austenitic Stainless Steel

Nitrogen‐Enhanced Temperature Dependence of Grain Refinement Strengthening in Austenitic Stainless Steel

Strengthening of CoCrNi medium entropy alloy with Ti additions

A series of (CoCrNi)100-xTix (x = 0, 1.0, 2.0, 3.0 and 4.0) medium entropy alloys (MEAs) was manufactured by high-vacuum arc melting in the present study to examine the effects of Ti additions on the microstructures and mechanical properties of the MEAs. For x = 0, 1.0 and 2.0, the alloys remained a single-phase FCC solid solution. The Ti(Ni, Co)3 precipitates of HCP phase formed for x = 3.0 and 4.0. The presence of Ti, which had the larger atomic radius than the other constituent elements, in the solid solution enhanced the lattice distortion and resulted in grain refinement. The addition of Ti led to the enhanced mechanical properties with the ultimate tensile strength and Vickers hardness increased from 866 MPa and 212 HV at x = 0 to 1490 MPa and 409 HV, respectively, at x = 4.0. The strengthening mechanisms of solid solution strengthening, grain refinement and precipitation strengthening were discussed, and the predicted strengthening was compared with measurements.

A study of Cu modified Ti–6Al–4V deposits fabricated by wire-arc directed energy deposition: Alloy design, microstructure, and mechanical properties

The addition of alloying elements during additive manufacturing increases the strength but always sacrifices ductility. Therefore, simultaneously enhancing strength and ductility is still the focus today. In this study, Cu was selected as the alloying element, and the optimal Cu addition (1.2 wt%) was re-alloyed and predicted using Thermo-Calc software combined with a single-bead deposition experiment, followed by alloying into feeding wire. Ti–6Al–4V-1.2Cu was compared with commercial Ti–6Al–4V deposits, and it was found that both microstructures consisted of prior β, GB α, and basketweave structures containing α+β lamellae. The introduction of Cu realized the refinement of prior β grains (836 ± 12 μm→592 ± 8 μm), the refinement of α laths (2.56 ± 0.06 μm→1.91 ± 0.04 μm), the coarsening of β laths (0.03 ± 0.005 μm→0.2 ± 0.03 μm), and the refinement of GB α (0.9 ± 0.07 μm → 0.45 ± 0.04 μm). As a β stabilizer, Cu increased the residual β content in the final microstructure (8.89%→18.67%). No formation of brittle Ti2Cu means that only grain refinement strengthening and solid-solution strengthening matter. The yield strength increased from 868.23 MPa to 934.32 MPa (7.61% increase). Among them, the contribution ratio of grain refinement strengthening and solid solution strengthening was the same through quantitative analysis. The ultimate tensile strength increased from 934.97 MPa to 990.97 MPa (6% increase). At the same time, tensile fracture elongation increased from 6.35% to 10.66% (67.87% increase), while the fracture mode transits from brittle cleavage to ductile dimples. Grain refinement of prior β grains, α laths, and GB α, inhibition of the β→α′ martensitic transformation, and local misorientation change of α laths are the main factors in improved ductility. In addition, the UTS and EL results are compared with earlier studies to reveal the prospect of this research.

Study on the in situ strengthening and toughening mechanism of H13 tool steel/WC-12Co composite using laser-based directed energy deposition

To overcome the unworkability of hot work molds in conventional manufacturing, laser additive manufacturing (AM) is widely adopted to print molds/dies with complex internal structures. However, in the AM process, some hot work steels easily crack (e.g., H11 and H13 tool steel) or exhibit dissatisfactory wear resistance (e.g., MS1 maraging steel). To tackle this issue, toughened functionally graded metal matrix/ceramic composite materials can be fabricated on existing molds by laser directed energy deposition (L-DED). Contrary to previous studies that clad Co on WC to avoid the decomposition of ceramic, in this work, we innovatively utilized a type of WC-12Co powder with a substructure to accelerate its decomposition and improve the toughness of composites. It was found that the unmelted tens-micrometer-magnitude WC-12Co powder and in situ synthesized nano WC coexist in the laser-deposited H13 steel/WC-12Co composites to act as the reinforcement phase. Particularly, all the brittle phases (WC and FexWxC) are wrapped by soft γ phases, alleviating the coefficient of thermal expansion (CET) mismatch between materials and the residual stress generated by laser AM. Consequently, defect-free deposits with varied WC contents are manufactured by L-DED and exhibit high hardness and superior wear resistance at both room and elevated temperatures due to the second phase and grain refinement strengthening mechanisms. These findings provide a disparate metal matrix composite design route for laser additive manufacturing to improve the toughness of metal matrix/ceramic composite materials and obtain exceptional performance.

Effect of Mischmetal Addition on Microstructure and Mechanical Properties of As-Cast and As-Rolled Mg–Sn–Ca Alloys

The microstructures and mechanical properties of Mg–3Sn–0.1Ca–xMM (mischmetal, x = 0.3, 0.6, and 0.9 wt.%) alloys were investigated. Optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) were used to characterize the microstructures and phase constitutions of the cast and rolled alloys. Room temperature tensile tests were conducted to obtain the mechanical properties and macro-textures to evaluate the texture weakening effect results of the MM. The results show that an abundance of second phase formed, confirmed as the (Ca,MM)MgSn phase, and the volume fraction increased with the increasing MM addition. The tensile yield strength of the as-cast alloys increased with the MM addition, but the elongation decreased. All of the rolled Mg–3Sn–0.1Ca–xMM alloys showed a strong basal texture, and only slightly decreased in intensity after annealing treatment due to the particle-stimulated nucleation of recrystallization. The as-annealed Mg–3Sn–0.1Ca–0.6MM alloys exhibited the highest tensile strengths of 266.5 ± 3.3 MPa and 136.1 ± 3.7 MPa, which are mainly ascribed to grain refinement strengthening, Orowan strengthening and texture strengthening.

Thermophysical and mechanical properties of dual-phase medium- and high-entropy rare-earth zirconate ceramics

The medium-entropy ceramic (La1/3Nd1/3Gd1/3)2(Zr3/4Ce1/4)2O7 and high-entropy ceramic (La1/5Nd1/5Sm1/5Eu1/5Gd1/5)2(Zr3/4Ce1/4)2O7 were successfully synthesized. The two ceramics had a pyrochlore-fluorite dual-phase structure, and they exhibited excellent phase stability at elevated temperature. Grain refinement or solution strengthening improved the Vickers hardness, fracture toughness and elastic modulus of the dual-phase ceramics. Compared with the single-element ceramic La2Zr2O7, multicomponent doping resulted in a significant increase in the thermal expansion coefficient. Simultaneously, the thermal conductivity of the dual-phase ceramics was lower than that of single-phase ones. In addition, on account of the large size disorder parameter of the medium-entropy ceramic, the thermal conductivity could outperform its high-entropy counterpart. These results indicate that pyrochlore-fluorite dual-phase rare-earth zirconates have enormous potential in applications concerning next generation thermal barrier coatings.

Effect of G-phase and heterogeneous deformation-induced strengthening on the mechanical properties of Cu-20Ni-20Mn-2Fe-1Si alloy

It is a challenge to simultaneously improve the strength and plasticity of ultra-high strength and high elasticity copper alloys. A synergistic strengthening strategy of heterogeneous deformation-induced strengthening (HDI) and grain refinement strengthening is proposed. Cu-20Ni-20Mn-2Fe-1Si has been designed according to this strategy. The addition of Si formed G-phases (Mn6Ni16Si7) in the alloy, which have an average size of 1 μm and a volume percentage of about 9.36%. There is a significant hardness difference between the Cu-rich phases and the G-phases, and the large strain gradient during deformation leads to HDI strengthening. After 75% cold rolling, solid solution at 830 °C for 2 h, and aging at 450 °C for 88 h, a large amount of NiMn phases of about 4–8 nm precipitated in the alloy and the average grain size is about 2.8 μm. The tensile strength, yield strength, elastic modulus, and elongation of the alloy reached 1.37 GPa, 1.27 GPa, 149.4 GPa, and 6.04%, respectively. The calculation results show that precipitation strengthening, HDI strengthening, grain refinement strengthening, solid solution strengthening contribute 0.63 GPa, 0.45 GPa, 0.08 GPa, and 0.08 GPa to the total strength, respectively. All of these provide new ideas for the design of novel ultra-high strength and high elasticity copper alloys.

Strengthening metastable dual-phase Fe60Cr15Ni16Al9 complex concentrated alloy at cryogenic temperature by doping Ti and Mo

The Fe-based complex concentrated alloys (Fe–CCAs) show great potential for advanced structural materials due to their vast alloy compositional spaces, outstanding mechanical properties and low cost of raw material. However, the yield strength of most Fe–CCAs at cryogenic temperature is insufficient, limiting their load-bearing applications under extreme service conditions. In the present work, the additions of Ti and Mo are employed to enhance the tensile properties of metastable dual-phase Fe60Cr15Ni16Al9 CCA. The results show that the yield strength is obviously increased without sacrifice of ductility by substituting the Ti and Mo for Al element. At 77 K, the obtained Fe60Cr15Ni16Al7Ti1Mo1 CCA exhibits superior combination of yield strength and ductility (∼1420 MPa and 35%). The increment of yield strength can be explained by the refinement strengthening and solid strengthening induced by doping Ti and Mo. Moreover, adding Ti and Mo will lower the rate of phase transformation and thus retain a relatively stable strain-hardening stage, which finally achieves exceptional ductility. This work provides an effective way to synergistically increase the yield strength and ductility of metastable dual-phase CCAs.

Stress corrosion cracking behavior of AISI 316L stainless steel treated by surface mechanical grinding

The effects of surface mechanical grinding treatment (SMGT) on stress corrosion cracking (SCC) behavior of machined 316L stainless steel surface were investigated by comparing to those of turned and milled surfaces. The surface stress state, roughness, microstructure, and microhardness induced by the different surface machining processes were tested and analyzed. The SCC tests on the turned, milled and SMGT samples were conducted in boiling MgCl2 solution at 155 ℃, and the crack morphologies were analyzed in detail to establish the relationship between the surface integrities and the resulting SCC behavior. The findings indicated that the SMGT altered the SCC initiation behavior and improved SCC resistance of the turned and milled surfaces of 316L stainless steel, and the surface stress state, microstructure refinement and surface strengthening induced by SMGT contributed to the improvement of the SCC resistance.

Microstructures and the improved mechanical properties of AZ91 alloy by incorporating Ti-6Al-4V particles

Magnesium (Mg) based composites are often difficult to achieve the trade-off between strength and ductility. The titanium (Ti) metal particles, which show better wettability and ductility than ceramic particles, are selected as reinforcements to simultaneously enhance the strength and plasticity of Mg alloys. In this work, the TC4 (Ti-6Al-4V) particles (2, 4 and 6 vol %) reinforced AZ91 composites were successfully fabricated by the mechanical and ultrasound-assisted stirring method. By incorporating 4 vol% TC4 particles, the composite reached the optimum yield stress, ultimate tensile stress, and elongation of 257 MPa, 370 MPa and 18.7%, respectively. The microstructural characterizations revealed that the fine and coarse grains were observed in the AZ91 and TC4/AZ91 composites. The dynamic recrystallization behavior was retarded in the TC4/AZ91 composites, which was rooted in the TC4 particles and fine Mg17Al12 phase. Transmission electron microscopy (TEM) showed that the interfacial product at TC4/Mg interface was Al3Ti phase. Based on the quantitative calculations, the strengthening effects of the 4TC4/AZ91 composite were mainly the coefficient of thermal expansion strengthening, grain refinement strengthening and the deformable TC4 particles.

Effect of recrystallization on bainite transformation and mechanical properties of complex phase steel with high formability (CH steel)

Herein, the effect of recrystallization on the bainite transformation and mechanical properties of CH steel were investigated using SEM, TEM, EBSD, dilatometry, and tensile testing machine. First, precipitation was introduced to hinder recrystallization by batch annealing. Subsequently, the competitive relationship between austenite transformation and recrystallization was revealed using different annealing processes. Finally, the effect of recrystallization on bainite transformation was analyzed, mainly including bainite morphology, fraction, transformation rate, bainite nucleation rate of untransformed austenite and austenite-bainite orientation relationship, as well as the effect on the mechanical properties. After batch annealing, a large amount of cementite and nanoscale (Nb, Ti)C precipitated in the hot-rolled sheet, the austenite transformation start temperature (Ac1) and the pearlite to austenite transformation end temperature (Ac1f)of the cold-rolled sheet increased, and the austenite transformation end temperature (Ac3) of the cold-rolled sheet decreased, and the austenite transformation process accelerated. The microstructure of annealed sheets is consisted of ferrite, granular bainite, martensite, and a small fraction of retained austenite. Carbide hindered the recrystallization process during the annealing process, resulting in significant refining of the grains. The lower degree of recrystallization promoted bainite transformation, providing more nucleation sites, higher grain boundary and autocatalytic nucleation activation energy, improving bainite's fraction and transformation rate. The bainitic ferrite was mainly lathy in the recrystallized zone and polygonal in the non-recrystallized zone. Both a K-S and an N-W relationship between retained austenite and bainite, while the N-W relationship in the non-recrystallized zone was relatively higher. Without severe loss of plasticity, hindering recrystallization increased the dislocation, grain refinement, and precipitation strengthening values of the samples, and the strength significantly improved. However, with the increase of annealing temperature, recrystallization fraction increased gradually, and the increase in strength became less noticeable.

Microstructural design for achieving high performances in Ti-V-Al lightweight shape memory alloys by optimizing Zr content

In the present study, the quaternary Zr element was introduced to replace Ti in Ti-V-Al based shape memory alloys. The addition of Zr element resulted in the microstructural features of Ti-V-Al based shape memory alloys, such as the phase evolution of αˊˊ → β, the precipitation of C14-type Laves phase, reduction of grain size etc. Moreover, the two-stage martensitic transformation corresponding to ω → β and αˊˊ → β transformation gradually evolved into single ω → β martensitic transformation during heating process in Ti-V-Al based shape memory alloys, as Zr content was increased from 0.5 at.% to 5.0 at.%, which was firstly reported in Ti-V-Al based shape memory alloys. Meanwhile, the martensitic transformation temperatures of Ti-V-Al based shape memory alloys were decreased with Zr increasing. By optimizing Zr content, the highest yield strength and largest microhardness can be gained in Ti-V-Al based shape memory alloy with controlling 5.0 at.% Zr, as a result of solution strengthening, grain refinement and precipitation strengthening. Besides, the moderate Zr content caused the precipitation of C14-type Laves phase and formed the quasi-continuous network structure, which contributed to the superior elongation. And the perfect fracture ductility with an elongation of 40% in the present Ti-V-Al based shape memory alloys with 3.0 at.% Zr was significantly larger than that the other reported Ti-V-Al based shape memory alloys. Moreover, the superior strain recovery characteristics with a fully recoverable strain of 4% can be achieved in Ti-V-Al based shape memory alloys through controlling 3.0 at.% Zr.

Effect of extrusion and rotary swaging on the microstructural evolution and properties of Mg-5Li-5.3Al-0.7Si alloy

High-strength Mg–5Li-5.3Al-0.7Si alloys were prepared by applying a combination of conventional extrusion with an extrusion ratio of 25:1 at 320 °C and subsequent rotary swaging (RS) with 0.2 mm reduction per pass in diameter at room temperature. The microstructural evolution was characterized and mechanical properties were investigated by tensile tests. The EBSD results showed that the grain size of the alloy decreased remarkably after extrusion and RS. Meanwhile, the yield strength (YS) of the as-extruded alloy was significantly improved from 161 MPa to 301 MPa by 2 passes RS, with only a slight reduction in ductility. The grain refinement during RS should be attributed to the activation of twins and continuous dynamic recrystallization (CDRX). The texture evolution during RS was investigated by EBSD. The number of grains with <0001> parallel to extrusion direction (ED) decrease significantly after RS. These grains are subjected to multi-directional stress and deformation, which rotate and develop a stronger texture component with <101‾0> - <112‾0> parallel to ED during RS, leading to the optimization of grain orientation. The phase evolution was investigated by SEM, EDS and TEM. Extrusion and RS effectively crush and disperse the second-phase particles of Mg2Si and Al0.89Li0.11, leading to their homogenization and refinement. The main mechanisms for strengthening the as-swaged alloy include grain refinement strengthening, dislocation strengthening, and second-phase strengthening. Grain refinement strengthening plays a dominant role in the as-swaged alloy.

Microstructure evolution, mechanical properties, and wear behavior of in-situ TiCx/TC4 composites

In this work, In-situ TiCx/TC4 composites were fabricated using Ti3AlC2 as a precursor via vacuum hot-pressing sintering. The effect of Ti3AlC2 content on the microstructure, mechanical properties, and wear behavior of TC4 matrix composites was investigated. The results indicate that the TiCx phase formed from the reaction between Ti3AlC2 and Ti during sintering. The in-situ formation of the TiCx phase could refine the size of the prior β grain and alter the microstructures of the matrix from the Widmanstatten structure of neat TC4 to an equiaxed structure. The TC4 matrix composites with different amounts of Ti3AlC2 exhibited higher hardness, yield strength, and tensile strength than neat TC4. When the volume fraction of Ti3AlC2 was 2.5%, the yield strength and tensile strength of composites were 951.2 MPa and 1033 MPa, respectively, which increased by 16.5% and 9.4% compared to neat TC4, respectively. Moreover, the elongation of the composites was 12.8% with substantially maintained plasticity. The improvement of yield strength in the composites is attributed to grain refinement strengthening and load transfer strengthening. The wear behavior of in-situ TiCx/TC4 composites was enhanced significantly. Abrasive wear and adhesive wear are the dominant wear mechanism in the TiCx/TC4 composites.

Plastic deformation behavior and strengthening mechanism of SLM 316L reinforced by micro-TiC particles

In this work, the integrated study on the microstructure evolution, plastic deformation behavior, and strengthening mechanism of Selective Laser Melting (SLM) 316L austenitic stainless steel (ASS) reinforced with micro-TiC particles was investigated. The results indicated that there were lots of small angle grain boundaries in SLM 316L ASS, and the high dislocation density and component segregation of the cellular dislocation structure resulted in a good combination of high strength and good elongation in performance. The tensile strength, yield strength, and elongation of SLM 316L ASS were 682 MPa, 571 MPa, and 49.9%, respectively. The addition of TiC reinforced particles induced microstructure evolution, including grain refinement, reduction of epitaxial columnar dendrites, reduction of low angle grain boundary (LAGB) ratio and increase of Σ3 (60°/<111>) twin boundaries. Through the effects of grain refinement strengthening, Orowan strengthening, and dislocation strengthening, SLM 316L-2TiC showed a higher tensile strength of 1021 MPa and higher yield strength of 809 MPa, while maintaining an elongation of 30.8% due to the suppression of plasticity by twinning induced plasticity (TWIP) effect. Although nano-reinforced particles were commonly used to improve mechanical properties, in our work, we chose to add micrometer-sized TiC particles, and the strength of the SLM 316L-2TiC metallic matrix composites (MMCs) exceeded the previous reports of adding nanoparticles. The reason was that the small contact angle between TiC and 316L provides good wettability between the particles and the melt, and the selection of laser processing parameters ensures good bonding between TiC particles and the substrate.