Microstructure and Mechanical Properties of Spray-deposited Al-20Si-5Fe-3Cu-1Mg Alloy

The Microstructure and Mechanical Properties of the Alloys in Journal of University of Science and Technology Beijing in August 1998 Wang Feng, Yang Bin, Cui Hua, Duan Xianji, Zhang Jishan, State Key Laboratory of New Metal Materials, University of Science and Technology Beijing, Beijing 100083, China Microstructure and mechanical properties were analyzed. Six pairs of alloys were extruded and heat treated after the microstructure changes. The tensile test results show that the spray deposits 1205 KH of man; the 3 old 8 alloy has a higher temperature 300 than the powder metallurgy 1208138 alloy and the strength.

Classification No. D, 146.2 When the common eutectic 18 alloy was produced by a common casting process, the slow cooling rate resulted in the formation of coarse plate-like phases in the alloy. They severely fractured the continuity of the alloy matrix and were stress-concentrated when loaded. Under the action of the alloy, the elongation of the alloy is significantly reduced, so the strength of the material is low and the plasticity is poor, and the use value is lost in the project. The rapid solidification technique can effectively change the morphology and size of the primary crystal 8 in the hypereutectic 5 alloy, significantly improving the performance of the alloy.

Spray deposition is a new type of rapid condensation technique. It atomizes liquid metal into liquid droplets. Under the action of high-speed inert gas, the droplets rapidly cool and then deposit on the receiving substrate to form a shaped deposit. Pieces. Compared with the powder metallurgy technology, the two processes of metal atomization and atomization droplet deposition are completed in the step metallurgical operation, which overcomes the disadvantages of the complex oxidation process of the powder metallurgy process.

In order to improve the room temperature performance of hypereutectic 18 alloy, Cu, Mg and other elements are usually added to the alloy. However, when such alloys are used as materials used at high temperatures, such as engine pistons, their strength is unsatisfactory. This is because 8 is used as a precipitation strengthening element and its precipitated phase is relatively low in the alloy. In order to improve the strength of the alloy at high temperatures, a transition element FeNi or the like is usually added to the alloy. Because Fe has a high diffusion coefficient in the liquid Al 81 alloy, it is low in the solid state. 19991228 Received by Wang Feng, male, 32 years old, Ph.D. in a given number, can form 1,816 metal rooms under spray forming conditions Compounds, so that the thermal stability of the alloy is significantly improved.

The microstructure and mechanical properties of the alloy were analyzed. The effect of six pairs of deposited alloys on the microstructure changes during extrusion and heat treatment was analyzed.

1 Test method The mass fraction of the alloy used in this experiment is 3,20; with the ring-hole nozzle, the atomizing gas is N2, the gas pressure is 0.60.83, the melt temperature during spraying is 750,850, and the diameter of the draft tube is 3mm The deposition distance is 400mm; the deposited blank is processed into a round bar with a stomach diameter of 0 and is hot-extruded at 4001. The extrusion ratio is the air-cooling of the extruded material. After extrusion, the alloy was treated with D 6 heat treatment 4701, solid solution 1.5 quench water, natural aging 4 hill 120, artificial aging 241, the microstructure of the alloy was observed and analyzed using an 8360 scanning electron microscope and a Japanese diffractometer. The tensile test was performed on an MTS810 test machine. The stretching speed is 0,05 mVs.

2 Results and Discussion 2.1 Spray Deposited 2081531 Elbow 8 Alloy microstructure Microstructure of gold and surface distribution of Fe and Si elements. From 1 can be traced, its hung-weaving foot matrix and indium granular or acicular first phase were woven into the chamber as a force alloy deposited scattering 61 images, it is clear that the needle-like buckle and less mechanical particles phase The composition is similar, 1 phase, 1 foot, and Shan are respectively 3 yuan, tired and tired. With the combination of gold, inter-compounds. Acupuncture, while the prime phase is granular, the particle size of the average person is about 4.

Spray-deposited materials can be classified into two distinct, closely related phases in the form of micro-structures. In the first stage, the atomized droplets undergo rapid quenching of the short loop, and some of the droplets are formed with a relatively small amount of weaving. The droplets arrived at the deposition stage and the 6th stage officially started. At this time, Pan considers the change from micro-weaving when I meet. For an anvil 5 alloy, the cooling rate of atomization over the quotient quotient effectively changes the quotient of the deposited semi-condensate (six) droplets on the sinking surface, not only causing atomized droplets, but also Deformation and fracture, and several also began to form deformation and fragmentation along the buckle in the semi-contaminated area, so that the deposition along the core of the core of the skin, increase, and provide a driving force for the 5-phase nucleation, and The phase remains granular.

Pavilion 2 is an injection-deposited 2053, alloy extruded state and 6 heat-treated state with micro-structure, can be spring-rolled from 2 to 43-gauge pressed state and published state of heat treatment, Under the effect of heat and deformation, the needle-shaped intermetallic compound is extruded into a short rod shape, and the large-sized and irregularly shaped initial product of the individual scales is crushed, and they are evenly distributed on the alloy matrix; the extruded alloy is passed through the die 6 After the heat treatment, the shape of the early product 8 phase becomes more rounded and its size does not change. This is because the 81-phase growth process of the yttrium is realized by the long-distance diffusion of 81 atoms from one particle to another. The alloys formed after the addition of the alloy; 136 intermetallic compounds, which reduced the number of 5 jobs. On the other hand, the intermetallic compound containing 1 is distributed in the grain boundary sub-material boundary and in the crystal in a small size after being squeezed, effectively submerging the vacancies for long-distance diffusion, and becomes an obstacle to diffusion, especially in the product boundary and the like. The junction of the gold-diffusion compound causes difficulty in the diffusion of eight atoms and the growth of five phases.

Pavilion 3 is a 1205531 alloy sink-state extrusion state and D 6 heat treatment state, ray diffraction. From the pavilion, it can be seen that the as-deposited alloy contains metastable phases 1 and 812, and the extrusion is under heat and deformation in the joint state, and they are transformed into a stable phase.

12 Mechanical properties of spray forming 2081531 Alloy It is known that spray forming 186 alloy obtained higher strength properties after 400 hot extrusion and D6 heat treatment, and it has strength of 1 alloy. This is due to the fact that the addition of 6 has formed a 136-element metal compound in the alloy. In the heat treatment of extrusion and D6, they changed the alloy's refinishing behavior by inhibiting the substructure disappearance and the boundary migration. The coarsening of the structure improves the room temperature strength of the alloy. In addition, in the high temperature conditions, 1516 yuan gold. The 4 compounds themselves have a relatively high thermal stability, and at the same time, they have the effect of hindering 8 phase particle alloy addition, geisha shot deposition +4oor hot extrusion; +6 heat treatment powder metallurgy + 400X hot extrusion + D 6 heat treatment 3 conclusions 1 Spray forming rapid condensing, technical station change, overgynolds 18 alloy primary crystal, phase morphology and distribution, which is a high cooling rate in the process of mountain jet deposition changed the 81-phase growth morphology, in addition, the deposition process atomized liquid The rapid collision between droplets and sedimentation increases the density of the phase core, which increases the driving force of the phase nucleation and makes the initial phase of the product.

Granular.

A large amount of acicular intermetallic compound phase 5 is formed in the microstructure, and the metastable 6512 phase is transformed into a stable one phase after extrusion, and the shape changes from a long needle to a short rod. Due to their higher thermal stability, the alloys change the refinish behavior of the alloy during extrusion and 16 heat treatment, reducing the 8 phase coarsening and increasing the strength of the alloy. After extrusion and heat treatment with D6, the tensile strength of the alloy at 300°C reaches 274MPa, which greatly exceeds the high-temperature strength properties of the spray-formed ASi4UMg alloy.