Selective laser melting of a high strength Al-Mn-Sc alloy: alloy design and strengthening mechanisms

Recent advances in ageing of 7xxx series aluminum alloys: A physical metallurgy perspective

Aerospace is a key market driver for the advancement of additive manufacturing (AM) due to the huge demands in high-mix low-volume production of high-value parts, integrated complex part geometries and simplified fabrication workflow. Rapid and significant progress has been made in the laser additive manufacturing (LAM) of aeroengine materials, including the advanced high-strength steels, nickel-based superalloys and titanium-based alloys. Despite the extensive investigation of these three families of materials by the research community, there is a lack of comprehensive review on LAM of high strength steels, and existing gaps in published reviews on Ti-based alloys and Ni-based superalloys. Furthermore, although emerging materials such as high/medium entropy alloys and heterostructured materials exhibit promising mechanical performance, rigorous characterization, testing, qualification, and certification are still required before actual application in engine parts. Thus, it is still important and relevant to have a deep understanding on the relationship between process parameters – microstructures – mechanical properties in these widely used aeroengine materials, to drive the development of superior high-value alloys. This review aims to provide a critical and in-depth evaluation of laser powder bed fusion (LPBF) and laser directed energy deposition (LDED) technologies of the mentioned aeroengine materials. The review will summarize the material properties, performance envelops and outlines the research gaps of these aeroengine materials. Furthermore, perspectives on research opportunities, materials development, and new R&D approaches of LAM for the aeroengine materials are also highlighted.

Progress and perspectives in laser additive manufacturing of key aeroengine materials

Isothermal compression tests of a new type Al–Zn–Mg–Er–Zr alloy are carried out on a Gleeble-3800 thermal simulator at temperatures varying from 300 to 460 °C and strain rates ranging from 0.001 to 10 s −1 . A comprehensive and scientific constitutive models based on the Arrhenius type equation have been developed from the experimentally measured data. The deformation temperature and strain rate have significant effect on flow stress and the material constants, such as α, β, n, ln  A and Q are the functions of the strain. The flow stress calculated by the developed constitutive equation shows a close agreement with the experimental value, which indicates that the proposed constitutive equation can precisely analyze the hot deformation behavior of the Al–Zn–Mg–Er–Zr alloy. Due to the presence of coherent L1 2 -structured Al 3 (Er,Zr) precipitates, the dominant softening mechanism is dynamic recovery during isothermal compression.

Hot deformation behavior and constitutive equation of a new type Al–Zn–Mg–Er–Zr alloy during isothermal compression

Towards a high strength aluminium alloy development methodology for selective laser melting

Hot deformation behavior and processing map of a new type Al-Zn-Mg-Er-Zr alloy

The effects of homogenization treatments on the precipitation behavior of Al 3 (Er,Zr) particles and theirs effects on recrystallization resistance in a new type Al-Zn-Mg-Er-Zr alloy have been investigated. Four different homogenization treatments, conventional one-stage homogenization, double-stage homogenization and ramp heating homogenization are carried out. Compared with that in the conventional one-stage homogenization, a finer particle size, higher number density and volume fraction of Al 3 (Er,Zr) particles can be obtained in other three homogenization treatments. In addition, the double-stage homogenization and the ramp heating homogenization can improve the Al 3 (Er,Zr) particles distribution and minimize the width of precipitation free zone in the region near the grain boundary, and provide an additional but nonnegligible strengthening effect for the Al-Zn-Mg-Er-Zr alloy. The difference in precipitation behavior of Al 3 (Er,Zr) particles lead to different recrystallization resistance. The high recrystallization resistance can be attributed to the larger f V /r ratio of Al 3 (Er,Zr) particles, which resulting in a higher Zener drag to effectively resist the recrystallization in Al-Zn-Mg-Er-Zr alloy during hot deformation and the subsequent thermal processing. Therefore, under the same annealing time, the double-stage homogenized and the ramp heating homogenized samples can achieve a significant lower recrystallized fraction compared with the conventional one-stage homogenized samples.

Effects of homogenization on precipitation of Al3(Er,Zr) particles and recrystallization behavior in a new type Al-Zn-Mg-Er-Zr alloy

Microstructural tailoring of As-Selective Laser Melted Ti6Al4V alloy for high mechanical properties

Precipitation hardening and recrystallization behavior of AlMgErZr alloys

A study on the precipitation hardening and recrystallization behavior of dilute Al–Er–Hf and Al–Er–Hf–Zr alloys has been carried out. The results show that both Al–0.045Er–0.18Hf and Al–0.045Er–0.08Zr–0.1Hf alloys can obtain remarkable age strengthening effect and recrystallization resistance. The precipitation hardening rate of Al–0.045Er–0.08Zr–0.1Hf is accelerated compared with that of the Al–0.045Er–0.18Hf alloy due to substituting 0.08 at% Zr for Hf, which can be ascribed to the sequential precipitation of solute elements on the basis of the disparity in their intrinsic diffusivities (DEr>DZr>DHf). The peak hardness values for the Al–0.045Er–0.08Zr–0.1Hf are 644 MPa and 662 MPa after isochronal aging to 450 °C and isothermal aging at 350 °C for 84 h, respectively, which are higher than those of the Al–0.045Er–0.18Hf alloy. The recrystallization temperature of Al–Er–Hf–Zr alloy is 450 °C, about 25 °C higher than that of the Al–Er–Hf alloy due to the larger f/r ratio of precipitates in Al–Er–Hf–Zr alloys.

X.L. Wu

Papers

Hot deformation behavior and processing map of a new type Al-Zn-Mg-Er-Zr alloy

Effects of homogenization on precipitation of Al3(Er,Zr) particles and recrystallization behavior in a new type Al-Zn-Mg-Er-Zr alloy

Microstructural tailoring of As-Selective Laser Melted Ti6Al4V alloy for high mechanical properties

Precipitation hardening and recrystallization behavior of AlMgErZr alloys

A study of precipitation strengthening and recrystallization behavior in dilute Al–Er–Hf–Zr alloys