Synergetic influence of microconstituents on the damage accumulation and consequent effect on the flow behaviour in cast Mg–Ca–Sn alloys

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2021-01, Vol.799, p.140167, Article 140167
• Main Authors: Koundinya, N.T.B.N., Kottada, Ravi Sankar
• Format: Article
• Language: English
• Subjects: Calcium; Cast magnesium alloys; Cracking (fracturing); Damage; Damage accumulation; Deformation; Hardening rate; Lamellar eutectic fraction; Magnesium base alloys; Microstructure; Morphology; Solid solutions; Strain analysis; Strain hardening; Tin base alloys; Yield strength
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2020.140167

Combined role of microconstituents (particles, eutectic fraction and its morphology) on the damage accumulation of three as-cast Mg–Ca–Sn alloys having distinctive microstructural features is studied. Flow stress normalized with that of a solid solution alloy brought out the sole contribution of microconstituents to the deformation. For identifying the influence of microconstituents on strain hardening rate, Kocks-Mecking analysis is utilized together with intermittent post-deformation microstructures. Comprehensive microstructural characterization as a function of strain facilitated to unravel the distinction in internal damage accumulation among the alloys. Further, the internal damage accumulation variation due to distinct variation in the microconstituents is attributed to the differences in hardening rate trends among the three alloys. The reduction in hardening rate is analyzed to occur due to damage accumulation through eutectic fracture or interphase cracking. Thus, the damage mechanism and its influence on strain hardening in cast magnesium alloys is proposed. •Damage accumulation with strain is dependent on the lamellar eutectic fraction.•Damage accumulation variation influences the hardening rate trend among the alloys.•Damage mode changes with variation in eutectic morphology (lamellar/divorced).•The interconnected divorced eutectic alloy exhibits higher hardening rate at ε>0.01•Combined role of microconstituents on damage is strain dependent.