Elasto-Plastic Deformation of Heterogeneous Metallic Materials: An Experimental Approach with AlMg4Si10

Abstract:

The increasing demand on thermo-mechanical strength, lightweight and formability in engineering applications require metallic materials with high sophisticated properties. Such functional alloys consist of heterogeneous composite-like microstructures, which are responsible for their stability in demanding service conditions (high temperature strength, low fatigue and creep resistance). External loads are distributed in between the phases of the alloys introducing high micro stress gradients, responsible for elastic and plastic deformation at the interfaces and micro crack initiation. Thus, the properties of such materials depend mainly on their phase shapes and 3D architectures leading to high stress gradients and elasto-plastic deformation under service conditions.This manuscript describes experimental studies on phase strain distribution for different heat treatment conditions in an AlMg4Si10 alloy. Neutron diffraction was used for strain measurement at an angle dispersive strain scanner with in-situ tensile test setup. Strain evolution under load and after unloading was measured to show elasto-plastic deformation behaviour in between the ductile α-Al matrix and stiff reinforcing Mg₂Si and Si phases. The degree of plastification, its effect on micro stress gradients and its influence on crack initiation could be discussed and comparisons to other composite materials could be drawn.

• Periodical: Materials Science Forum (Volume 1016)
• Pages: 1816-1822
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.1016.1816
• Online since: January 2021
• Authors: Michael Schöbel*, Domonkos Tolnai, Michael Hofmann
• Keywords: AlMgSi Light Alloy, Deformation Mechanisms, Heterogeneous Microstructure, Micro Stress Distributions, Neutron Diffraction, Solution Heat Treatment

References

[1] Garat M, Laslaz G, Improved aluminum alloys for common rail diesel cylinder heads, AFS Trans. 1-8 (2007) 07-02.

[2] Ostermann F, Anwendungstechnologie Aluminium, Springer Verlag, Berlin/Heidelberg (2007).

[3] Requena G, Garcés G et al. The Effect of Connectivity of Rigid Phases on Strength of Al-Si Alloys, Adv. Eng. Mat. 13 (2010) 647-684.

DOI: 10.1002/adem.201000292

[4] Molina R, Amalberto P, Rosso M, Mechanical characterization of aluminium alloys for high temperature applications Part 1&2. Al-Si-Cu alloys, Metall. Sci. Tech. 5-15 (2011) 29-1&2.

[5] Schöbel M, Baumgartner G et al. Microstresses and crack formation on AlSi7MgCu and AlSi17Cu4 alloys for engine components, Acta Mater. 81 (2014) 401-8.

DOI: 10.1016/j.actamat.2014.07.052

[6] Mondolfo LF, Al Alloys: Structures and Properties, Butterworth, London/Boston, (1976).

[7] Clyne TW, Withers PJ, An Introduction to Metal Matrix Composites. Cambridge University Press, Trumpington street, Cambridge CB2 1RP, (1993).

DOI: 10.1017/s0001924000050120

[8] Noreyan A, Qi Y, Stoilov V, Critical shear stresses at aluminum-silicon interfaces, Acta Mat. vol. 56 (2008) 3461-3469.

DOI: 10.1016/j.actamat.2008.03.037

[9] Tolnai D, Requena G et al. Effect of solution heat treatment on the internal architecture and compressive strength of an AlMg4.7Si8 alloy, Mat. Sci. & Eng. A 585 (2013) 480–487.

DOI: 10.1016/j.msea.2013.06.033

[10] F.R. Elsayed et al. Magnesium permanent mold Castings optimization Materials Science Forum 690 (2011) 65-68.

DOI: 10.4028/www.scientific.net/msf.690.65

[11] Hofmann M, Schneider R et al. The new materials science diffractometer STRESS-SPEC at FRM-II, Phys. B. 385-386 (2006) 1035-1037.

DOI: 10.1016/j.physb.2006.05.331

[12] http://www.frm2.tum.de, (2020).

[13] Hoelzel M, Gan WM et al. Rotatable multifunctional load frames for neutron diffractometers at FRM II – design, specifications and applications, Nuc. Inst. A. 711 (2013) 101-105.

DOI: 10.1016/j.nima.2013.01.049

[14] Schöbel M, Fernández R et al. Elasto-plastic deformation in Al-Cu cast alloys for engine component. Jour. of All. And Comp. (2019) 617-627.

DOI: 10.1016/j.jallcom.2018.10.109