Effect of extrusion ratio on the microstructure and property of the Al–Zn–Mg–Cu alloy prepared by spray conform

Abstract

The commercial Al-5.72Zn-2.36Mg-1.66Cu (7075) alloys were prepared by the spray Conform (SC) technique consisting of the spray forming and Conform extrusion. The extrusion ratio (ER) was selected as the variable parameter to study the influence mechanism on the microstructures and properties while keeping the other parameters unchanged. The microstructures and properties were investigated by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), x-ray diffraction (XRD), electron backscatter diffraction (EBSD) and tensile tests. Concretely, the changing rules of the grains, second phases, tensile strength and elongation with ER were researched respectively. Results indicate that a fine equiaxed grain microstructure with low level of segregation and porosity was achieved by SC. And the intergranular and intragranular phases were fine and homogeneous before and after retrogression and re-aging (RRA). The dispersion and tensile strength are positive to ER, but the grain size (GS) is inverse. Meanwhile, the elongation increases firstly and then decreases with increasing ER.

Direct continuous manufacturing Al–Zn–Mg–Cu alloy from a novel technology of spray-conform

“…Another phenomenon is that some large precipitates can be found at the grain boundaries and junctions [12]. Moreover, the grain boundaries present discontinuity and the precipitation free zones appear after RRA heat treatment (figures 7(b) and (d)).…”

“…With the development of social economics, the need for more economical processing method of manufacturing metals with high mechanical performance is more and more urgent. The Spray-Conform (SC) technology could be an alternative route to process the alloys of high elements continuously and economically without macrosegregation in the matrix metal [11][12][13]. The schematic diagram of the SC technology is shown in figure 1 [14].…”

A novel crucible-less inert gas atomisation method of producing titanium powder for additive manufacturing

“…When the atomisation gas pressure P 0 reaches 5.0 MPa, the D 50 of the powder is 35.8 μm at the minimum. In the process of atomisation, the effect of P 0 on D 50 is mainly expressed by the gas-liquid mass ratio (GMR) [16] formula:…”

“…When the atomisation gas pressure P 0 reaches 5.0 MPa, the D 50 of the powder is 35.8 μm at the minimum. In the process of atomisation, the effect of P 0 on D 50 is mainly expressed by the gas–liquid mass ratio (GMR) [16] formula: where GMR is the gas–liquid mass ratio, is the mass flow rate of gas, is the mass flow rate of liquid stream, μ is the discharge coefficient of atomising gas outlet, F is the total area of the atomising gas outlet, is atomisation gas pressure, is the density of atomising gas, m is the quality of metal liquid stream, and t is the effective atomisation time.

Figure 3 Average particle size of powders under different gas atomisation.

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“…Figure 1 shows the design and preparation of the WIGA device schematic. This equipment consists of the Ti wire, nozzle system, continuous feeding device [16], high-frequency induction coil system, cooling water system, gas cylinder system, vacuum equipment system and powder container system.

Figure 1 Schematic of the WIGA apparatus used in the preparation of titanium powder.

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