https://www.cavs.msstate.edu/publications/docs/2003/01/805Microstructure.pdf

Microstructure-based fatigue modeling of cast A356-T6 alloy

This review of multiscale modeling covers a brief history of various multiscale methodologies related to solid materials and the associated experimental influences, the various influence of multiscale modeling on different disciplines, and some examples of multiscale modeling in the design of structural components. Although computational multiscale modeling methodologies have been developed in the late twentieth century, the fundamental notions of multiscale modeling have been around since da Vinci studied different sizes of ropes. The recent rapid growth in multiscale modeling is the result of the confluence of parallel computing power, experimental capabilities to characterize structure-property relations down to the atomic level, and theories that admit multiple length scales. The ubiquitous research that focus on multiscale modeling has broached different disciplines (solid mechanics, fluid mechanics, materials science, physics, mathematics, biological, and chemistry), different regions of the world (most continents), and different length scales (from atoms to autos).

https://link.springer.com/content/pdf/10.1007%2F978-90-481-2687-3_4.pdf

Multiscale Modeling: A Review

https://www.cavs.msstate.edu/publications/docs/2004/01/749High%20cycle%20fatigue.pdf

High cycle fatigue of a die cast AZ91E-T4 magnesium alloy

The castability and properties of Al—Si based foundry alloys are affected by the inevitable introduction of impurity elements during melting and casting. Iron has consistently emerged as the most common impurity element that generally imparts negative influences on the soundness and mechanical properties of these alloys. It leads to the formation of iron-bearing intermetallics whose type, size, morphology and amount depend on the alloy composition, melt thermal history, cooling rate and post-casting heat treatments. These compounds, particularly their size and morphology, are the main culprits responsible for the significant influence of iron on the castability and mechanical properties. The most common of these compounds are β-Al5FeSi with a needle/platelet morphology, α-Al15Fe3Si2 with a Chinese script or polyhedron morphology and π-Al8Mg3FeSi6 also with a Chinese script morphology. The iron in the α phase can be substituted by Mn or Cr whereas the π phase forms when Mg is present. The β phase (the most...

Influence of iron on castability and properties of aluminium silicon alloys: literature review

https://www.cavs.msstate.edu/publications/docs/2003/01/754Cyclic%20plasticity.pdf

Cyclic plasticity at pores and inclusions in cast Al-Si alloys

r Mechanical fatigue tests were conducted on uniaxial specimens machined from a cast A356-T6 aluminium alloy plate at total strain amplitudes ranging from 0.1 to 0.8% (R = - 1). The cast alloy contains strontium-modified silicon particles (vol. fract. ∼6%) within an Al-Si eutectic, dispersed a intermetallic particles, Al 15 (Fe,Mn) 3 Si 2 (vol. fract. ∼1%), and an extremely low overall volume fraction of porosity (0.01%). During the initial stages of the fatigue process, we observed that a small semicircular fatigue crack propagated almost exclusively through the Al-1% Si dendrite cells. The small crack avoided the modified silicon particles in the Al-Si eutectic and only propagated along the a intermetallics if they were directly in line with the crack plane. These growth characteristics were observed up to a maximum stress intensity factor of ∼K tr max = 7.0 MPa m 1/2 (maximum plastic zone size of 96 μm). When the fatigue crack propagated with a maximum crack tip driving force above 7.0 MPa m 1/2 the larger fatigue crack tip process zone fractured an increased number of silicon particles and a intermetallics ahead of the crack tip, and the crack subsequently propagated preferentially through the damaged regions. As the crack tip driving force further increased, the area fraction of damaged a intermetallics and silicon particles on the fatigue fracture surfaces also increased. The final stage of failure (fast fracture) was observed to occur almost exclusively through the Al-Si eutectic regions and the a intermetallics.

Gall

Papers

The influence of modified intermetallics and Si particles on fatigue crack paths in a cast A356 Al alloy