ZL109 Alloy Research Articles

Determination of interfacial heat transfer coefficient at the frozen sand mold casting process of ZL101 alloy

Compared to the resin sand mold casting process, frozen casting is more environmentally friendly, providing a better working environment and enhanced supercooling degree. The interfacial heat transfer coefficient (IHTC) between frozen sand mold and metal is an important parameter that significantly influences the final mechanical properties and microstructure of the castings. This paper solved the inverse heat conduction problem using the finite difference method (FDM). In addition, the conjugate gradient method (CGM) was adopted to calculate the temperature distribution and heat flux in the molten metal. At the same time, the particle swarm optimization algorithm (PSO) was used in temperature distribution determination in frozen sand mold. The interfacial heat transfer coefficient (IHTC) was estimated during the solidification of ZL101. The results showed a good agreement between calculated and experimental data, obtaining accurate casting interface temperature Tm, frozen sand mold interface temperature Ts, heat flux q, and IHTC. The analysis of the IHTC variation revealed a water content value within the range of 4 wt.% to 5 wt.% resulted in IHTC in two types of interpretation, called ‘fluctuation type’ and ‘turning type’.

Effect of bias voltage on microstructure, mechanical and tribological properties of TiAlN coatings

TiAlN multilayer coatings composed of TiAl and TiAlN layers were deposited on ZL109 alloys using filtered cathodic vacuum arc (FCVA) technology. The effect of bias voltage on the microstructure and properties of the coating was systematically studied. The results show that the coating exhibits a multi-phase structure dominated by TiAlN phase. As the bias voltage increases, the orientation of TiAlN changes from (200) plane to (111) plane due to the increase of atomic mobility and lattice distortion. The hardness, elastic modulus and adhesion of the coating show the same trend of change, that is, first increase and then decrease. When the bias voltage is 75 V, the coating exhibits the highest hardness (~30.3 GPa), elastic modulus (~229.1 GPa), adhesion (HF 2) and the lowest wear rate (~4.44×10−5 mm3/(N·m)). Compared with bare ZL109 alloy, the mechanical and tribological properties of TiAlN coated alloy surface can effectively be improved.

Effect of nano h-BN particles on growth regularity and tribological behavior of PEO composite ceramic coating of ZL109 alloy

A composite ceramic coating containing h-BN particles was prepared on the ZL109 alloy via plasma electrolytic oxidation. The h-BN particles were modified by Polyethylene glycol to improve the dispersibility. The results revealed that the h-BN particles in the electrolyte were inertly incorporated into the coating. Meanwhile, the incorporation of h-BN particles can reduce the porosity and slightly increase the roughness of the composite ceramic coating. Furthermore, the growth rate of the coating and the conversion of γ-Al2O3 and α-Al2O3 were promoted by the incorporation of h-BN particles via the change of the current. In addition, due to the presence of h-BN particles, the composite ceramic coating had a lower friction coefficient and a lower wear rate under dry sliding condition.

Formation mechanism of TiC–Al2O3 ceramic reinforcements and the influence on the property of ZL101 composites

In this paper, Al2O3–TiC/ZL101 composites were fabricated via in-situ reaction process with TiO2, Al, graphite and ZL101 powders. Microstructure characteristics, formation mechanism of reinforcements, thermodynamic calculation of reaction, hardness and tribological behavior of the composites were investigated in detail. The distribution of Al2O3 and TiC precipitates changes from agglomerate to relative uniform with the content rise of strengthening phases. Al2O3 precipitates are irregular spherical with the average size of 3–5 μm. The shape of TiC particles is cube or polygon and the size is about 2–4 μm. The thermodynamic calculation of reactants further proves the reinforcements formation, which is consistent with the microstructure observation and X-ray diffraction result. The formation mechanism of TiC and Al2O3 mainly is by diffusion and precipitation. The microhardness and wear performance of composites remarkably improve, friction coefficient and wear weitgh loss decrease with the content rise of TiC and Al2O3 phases. The microhardness of C3 composite increases from 93HV to 162HV, the friction coefficient (FC) and weight loss decrease from 1.15 and 0.128g to 0.43 and 0.066g compared with the ZL101 alloy. C3 composite has the best wear property for the highest hardness, the lowest FC and weight loss. Microstructure refinement, uniform dispersion of TiC and Al2O3 precipitates and the strong interfacial adhesion between reinforcements and matrix are attributed to the better wear performance of composites. The wear surface morphology shows that the wear mechanism of ZL101 alloy is mainly adhesive wear while the wear style of the composites is abrasive wear.

Influence of silicon on growth mechanism of micro-arc oxidation coating on cast Al-Si alloy.

Micro-arc oxidation (MAO) is a plasma-assisted electrochemistry method to prepare protective ceramic coatings on aluminium alloys. Alloy elements of the Al-alloy substrate, such as Si, Cu, Mg and Li, have effects on the microstructure and composition of the MAO coatings. Usually, silicon distributes in the cast Al–Si alloy substrate as small laths and they cover approximately 10% of the substrate surface. Therefore, their effects on the growth process and microstructure of the MAO coatings are worthy of notice. In the present study, oxide coatings with a thickness of 15–18 µm were prepared on the ZL109 Al–Si alloy by MAO. The phase content, surface morphology and element distribution of the coatings were investigated by X-ray diffraction, grazing incidence X-ray diffraction, scanning electron microscope, and electron probe micro-analysis respectively. The average hardness of the coatings was 622.3 ± 10.2 HV0.05. The adhesive strength of the coatings is 40.55 ± 2.55 N, and the adhesion of the coatings could be rated as 5B by tape test according to ASTM D3359-17 standard test methods, which indicated a high adhesive strength between the MAO coating and substrate. The effects of silicon laths on surface morphology and composition of the coatings were discussed, and a model was put forward to describe the growth process of the MAO coatings on cast Al–Si alloys. The authors believe that the high silicon content of the substrate has no adverse influence on the structure and properties of the MAO coating on the ZL109 alloy.

Design and Improvement of the Investment Casting Process for the Ring-shaped Aluminum Alloy based on PROCAST software

The investment casting process of a ring-shaped ZL101 alloy is investigated based on PROCAST software, the alloy phase diagram and the thermophysical properties are analyzed. Besides, the initial casting temperature and the casting process were determined. After the analysis of the geometry model and temperature field model during the casting solidification process, results shows as: 1) the shrinkage and porosity is formed at the two sides and bottom end of casting pieces in the initial casting process, while slag inclusion is enriched at the top. 2) To avoid these two kinds of defects, the casting process is optimized and simulated. The simulated result is in compliance with the experiment, the agreement confirm that the improved process is reasonable. 3) The improved casting process is finally designed and the simulation shows that the experiment is in good agreement with the simulation results, which provides the actual guidence for the design of other casting pieces as well.

Microstructure and Properties of ZL101 Alloy Affected by Substrate Movement Speed of a Novel Semisolid Continuous Micro Fused-Casting for Metal Process

A novel semisolid continuous Micro Fused-Casting additive manufacturing technology for producing a ZL101 alloy strip was developed, Micro Fused-Casting means that the semisolid metal slurry was pressed out from the outlet of bottom of crucible to the movable plate. The degree of sub-cooling was easily provided by movement of substrate in the micro fused-casting area. Under the aid of 3D manufacturing software, the ZL101 alloy strip was solidified and formed layer by layer. The microstructure and properties of ZL101 semisolid slurry were improved by the cooling conditions. The results showed that the ZL101 alloy strip samples fabricated by Micro Fused-Casting had uniform structures and good performances with the substrate movement speed at 20 mm/s and the temperature at 590 °C, the ultimate tensile strength and elongation of the ZL101 alloy strip reached 242.59 MPa and 7.71%, while the average Vickers hardness was 82.55 HV.

Microstructure and properties of SiC/Gr composite reinforced aluminum matrix composites material

SiC/Gr/ZL101 aluminum-based composites were prepared by semi-solid stirring and gravity pouring method. The effects of SiC/Gr with different volume fractions on the microstructure and property of aluminum-based composites were studied by means of microstructure observation, tensile test, fracture scanning analysis and damping capacity test. The results show that the primary phase α-Al of ZL101 alloy prepared by semi-solid stirring and gravity pouring method is fragmented dendrite, along with the rising SiC volume fractions, the tensile strength of the composites first increases and then decreases while its elongation gradually decreases, the maximum tensile strength of the material can reach 168 MPa, up to 16% than that of ZL101 alloy, the fracture morphology is obviously brittle fracture. They also show that the addition of SiC and Gr improves the damping capacity of ZL101 alloy, the internal dissipation Q-1 of the composites is obviously higher than that of matrix alloy and gradually increases along with the rising SiC volume fractions. The damping mechanism of the composites is mainly the combined effects of both dislocation damping and interfacial damping.

Microstructure evolution during remelting of high solid fraction ZL101 alloy

This work deals with the reheating process for semi-solid thixoforming of ZL101 (AlSi7Mg) alloy. The semi-solid state can decrease the viscosity and the resistance while sheared because of the evolutional behavior, which is characterized by a solid-like behavior at rest and a liquid flow during shearing. The microstructure evolution of ZL101 alloy at different temperatures from 540 to 580 °C has been studied. Results show that the eutectic temperature can affect the transformation speed of semi-solid structure. Semi-solid microstructures with high solid fraction can be obtained by controlling the reheating time in less than 20min, while at the temperature lower than the eutectic temperature it needs more than one hour. Another character of semi-solid ZL101 alloy is the segregation of microstructures in semi-solid state, in which the liquid phase between the solid phases can flow freely and lead to the shrinkage of the sample during the heating process. As the holding time goes on, more shrinkage holes appear and change the surface of the specimen. These shrinkage holes are replenished by the liquid phase during compression deformation, resulting in the segregation of the components.

Characterization of the Hot Deformation Behavior of a Al-Si Alloy Using Processing Maps

The compression tests of solution treatment ZL109 alloy have been performed in the compression temperature range from 250°C to 450°C and the strain rate range from 0.0005s-1 to 0.5s-1. A processing map has been developed on the basis of flow stress data obtained as a function of temperature and strain rate, which revealed two domains of hot working for the alloy: one is situated at temperature between 270°C and 340°C with strain rate between 0.05s-1 and 0.5s-1, the other is situated at the temperature between 380°C and 450°C with strain rate between 0.0005s-1 and 0.004s-1. Combining with the processing map, the optimum parameters of hot working for ZL109 alloy are that 300°C/0.5s-1 and 450°C/0.0005s-1, respectively. Microstructure observations indicated that DRX occurred in both these domains. The instable zones, i. e., adiabatic shear bands formation, wedge cracking, were also identified in the processing map and microstructural examination was performed for validation.

Effect of Composite Master Alloy on Mechanical Properties and Electrochemical Corrosion of ZL101 Alloy

The mechanical properties and corrosion performances of the ZL101 alloy modified by the composite master alloy were investigated. The results showed that the master alloy had not only obvious effect of grain refinement, but also a significant role in refining dendrite grain of ZL101 alloy. The grain size decreased dramatically from 150μm to 62μm when the addition of composite master alloy is up to 0.5%(mass fraction) and the temperature is 720 for 30 minutes,. Its tensile strength and elongation increased by 27% and 42% respectively. The grain refinement of ZL101 alloy decreased its corrosion performance. The morphology of Si changed into globular from needle modified by NaF, instead of AlTiB.

Preparation Technology on Semi-Solid of ZL101

The semi-solid microstructure of ZL101 alloy was fabricated by technology of vibrating inclined cast. The effections of length of slope and vibration voltage on microstructure were also investigated. The experimental results showed that two parameters played an important role on the microstructure of ZL101 alloy. The homogeneous, small and rounded sphere-like semi-solid equiaxed crystals were obtained when the ZL101 alloy was cast in water-cooled copper mold with 25cm slope length at 640 °C and 60v vibration voltage, the average grain diameter and shape factor of which was 26.5um and 0.8, respectively.

Studies on Microstructure and Property of Material of SiCp/Gr/ Mixed and Reinforced Aluminum-Based Composites Prepared by Semi-Solid Pouring Method

SiCp/Gr/ZL101 aluminum-based composites is prepared by semi-solid stirring and gravity pouring method. The effects of SiCp/Gr with different volume fractions on the microstructure and property of aluminum-based composites are studied by means of microstructure observation, tensile test, fracture scanning and analysis and damping capacity test and analysis. The results show that the primary phase α-Al of ZL101 alloy prepared by semi-solid stirring and gravity pouring method is fragmented dentrite，along with the rising SiCp volume fractions, the tensile strength of the composites first increases and then decreases while its elongation gradually decreases, the maximum tensile strength of the material can reach to 168MPa, up to 16% than that of ZL101 alloy, the fracture morphology is obvious brittle fracture. They also show that the addition of SiCp and Gr improves the damping capacity of ZL101alloy, the internal dissipation Q-1 of the composites is obviously higher than that of matrix alloy and gradually increases along with the rising SiCp volume fractions. The damping mechanism of the composites is mainly the combined effects of both dislocation damping and interfacial damping.

Effect of Rare Earth La Modification on Microstructure and Properties of ZL101 Alloy

In this paper, rare earth La modifying ZL101 alloy was studied by using of optical microscope, scanning electron microscopy, universal materials tester and small-load Brinell hardness. The influence of T6 heat treatment of the alloy’s microstructure and properties was also studied. The results show that microstructure and mechanical properties of the alloy have much obvious modification effect at modification temperature (690°C). The microstructure and mechanical properties are improved remarkably when La content is up to 0.15wt%.

Fabrication of SiCp/ZL101 Composites Substrate with Near-Net-Shape

SiCp/Z101 composites substrate can be successfully fabricated by pressureless infiltration of ZL101 alloy liquid into porous SiCp preform, the relative density are nearly up to 99%. This is mainly because that generated SiO2phase on the surface after sintering of SiCp not only has joint function to the porous of SiC perform, but also obtains two-phase wetting between SiC and Al matrix through the interface reaction, resulting in promoting spontaneous infiltration. SiC preforms have almost no change of shapes and sizes after infiltration of Al liquid and can achieve near-net-shape of the composites for substrate. Volume fraction of SiC can be effectively improved by using binary mixture particles with the diameter ratio of 11:1, through which the properties of substrate can be controlled effctively. By the addition of SiCp, strength of the composites is improved remarkably, and its elastic modulus increases correspondingly about one time, the increase of SiC volume fraction can markedly reduce coefficient of thermal expansion (CTE) of composites , but meanwhile decrease thermal conductivity(TC) of composites, and its TC (at 50 °C ranges from 120.7 W/(m•k) to 99.4 W/(m•k) and its mean linear CTE (25°C to 50°C ) ranges from 9.47×10−6k-1to 7.05×10−6k-1as volume fraction of SiC ranges from 38% to 68%.

The structural evolutions of ZL109 alloy and 7050 alloy in the semisolid squeeze casting process

The structure evolutions of ZL109 alloy and 7050 alloy were studied in the processes of preparing raw billets by low super heat casting, remelting the raw billets, semisolid forming and heat treating components. The thin and symmetrical structure was obtained by using low super heat casting process. The eutectic that lied in the raw billet of ZL109 alloy remelted and produced liquid phase in the process of remelting, but to the 7050 alloy, the eutectic of intergranular and the pointedness of grains was remelted to make the grains more uniform and smooth. In the process of semisolid forming, the primary α and the eutectic inside the ZL109 alloy were separated partly and the grains in the 7050 alloy was conglutinated together. After heat treatment, the eutectic α grains of ZL109 traveled to primary α and shaped the white fishing net like organization; the eutectic Si grains assembled into the black massive particles. As to 7050, after heat treatment, α particles recrystallized and thin grains pattern was obtained.

Semi-solid squeeze casting process of a ZL109 alloy

The structure evolution of the ZL109 alloy in the process of semi-solid squeeze casting and the mechanical properties of the components were investigated. The results show that (1) the eutectic silicon phase in original billets is refined in the low super-heat casting process; (2) the eutectic structure in billets starts to fuse and the crystals of the eutectic silicon phase are refined further and sphericized in the remelting process of billets; (3) in the semi-solid squeeze casting process, the sphericity of the α phase and the refining of the silicon phase occur, owing to the friction between solid and liquid; (4) in the process of heat treatment, the eutectic α phase aggregates with the primary α phase and the eutectic silicon pieces aggregate together. The elongation of the semi-solid component after heat treatment rises to 1.42%.

Preparation of nanocrystal modificator and its modification mechanism

In order to increase the modifying effect, the Cu-P master alloy was rapidly solidified with melt-spin method, and the nano-sized ribbon was gained at 10 5–10 6 °C/s. Subsequently, ZL109 alloy was modified by nanocrystal and massive Cu-P master alloy, respectively, with molten metal casting method. The results show that the microscopic structure of ZL109 alloy modified by nanocrystal Cu-P master alloy is better than that modified by massive Cu-P master alloy, the original crystal silicon and eutectic silicon are refined more effectively and the mechanical properties are increased evidently: the tensile-strength is increased by 25%, the elongation is increased by 32.26% and the hardness is increased by 17.2%. Therefore, the melt-spin treatment is a feasible method to improve the modifying effect of Cu-P master alloy.

A novel method to induce the precipitation of primary silicon in commercial near eutectic Al–Si alloys

A novel method to induce the precipitation of primary silicon in near eutectic Al–Si alloy (ZL109) was investigated in this work. Ni–38 wt.%Si master alloy was added into the ZL109 alloy melt to induce the precipitation of primary silicon, and this technology was optimized by considering several parameters, such as the inducement temperature, the addition level, and the holding time. It was found that there was good inducement efficiency of Ni–38 wt.%Si master alloy for ZL109 alloy when the addition level was above 1% and held at 740 °C for above 30 min. Meanwhile, the efficiency can last for above 600 min. Finally, the precipitation of primary silicon in ZL109 alloy with Ni–38 wt.%Si master alloy was not induced by the increasing silicon containing, but induced by the addition of Ni–38 wt.%Si master alloy.

Relationship between microstructures and contents of Ca/P in near-eutectic Al–Si piston alloys

The relationship between microstructures and contents of Ca/P in near-eutectic Al–Si piston alloy (ZL109) was investigated by optical microscopy and electron probe microanalyzer (EPMA). Ca was found to have an obvious influence on the microstructures of ZL109 alloys. It is difficult to present phosphorus refinement effect when the Ca content in the ZL109 alloy exceeds 100 ppm. In order to obtain a good phosphorus refinement effect, the content of Ca impurity in the alloy should be under 50 ppm. It has also been shown that Ca can modify eutectic Si and enhance the formation of α-Al dendrites and fibrous eutectic Si in the alloy. Controlling the content of Ca impurity by the addition of C 2Cl 6 to the melt resulted in the appearance of phosphorus refinement effect. With the decrease of Ca content from 100 ppm to 12 ppm, the average primary silicon particle size is reduced to 16.2 μm from 31.7 μm.