The key quote of the workshop: “Al alloys of incredible strength were developed by Edisonian trial and error, over the course of 80 years. The science and engineering community will only permit us 5-10 years to make similar improvements to Mg alloys.” --- J.F. Nie. There was a consensus that the necessary theoretical, computational, and characterization tools are now available to make this dream a reality. 5
Breakout Discussions 5
1.Casting and Solidification 6
2.Alloy Development 8
3.Coatings and Corrosion 9
4.Mechanical Performance 11
Deformation Mechanisms 11
Dynamic Loading 13
Fatigue and Fracture 13
5.Deformation Processing (including Rolling, Extrusion, and Sheet Forming) 14
The recommendations expressed in this report are the collective opinions of the workshop participants. The participants were not required to provide citation or attribution for the work upon which the opinions are based. Nevertheless, experts in the respective fields were present to refute unsubstantiated claims or ideas that have limited merit.
12 invited speakers presented 11 lectures designed to set the tone for the smaller group discussions whose deliberations are summarized below. Full *.ppt or *.pdf presentation files containing their individual recommendations are available on-line via a password protected website: https://collab.itc.virginia.edu/portal/
Integrated Computational Materials Engineering (ICME) (John Allison, U. of Michigan)
Casting, extrusion, rolling and international collaboration (Karl Kainer, Helmholz Center, Geestacht, Germany)
Alloy design & Applications of modern hi-res probes (J.F. Nie, Monash U., Melbourne, Australia)
Coatings and Corrosion (Guangling Song, GM, and Robert McCune, retired Ford)
High strain rate performance (G.T. “Rusty” Gray, Los Alamos National Laboratory)
Alloy Design - CALPHAD, texture (Alan Lou, General Motors)
The key quote of the workshop: “Al alloys of incredible strength were developed by Edisonian trial and error, over the course of 80 years. The science and engineering community will only permit us 5-10 years to make similar improvements to Mg alloys.” --- J.F. Nie. There was a consensus that the necessary theoretical, computational, and characterization tools are now available to make this dream a reality.
Workshop attendees were broken up into a number of discussion groups on Thursday and Friday afternoons (see Appendix B). The results of those discussions are synthesized in the following eight sections: Casting and Solidification, Alloy Development, Coatings and Corrosion, Mechanical Performance, Deformation Processing, Joining and Fastening, Flammability and Aerospace Concerns, and Integrated Computational Materials Engineering (ICME). The following sections provide detailed recommendations in each of these eight areas.
Noteworthy absences in the list of topics are those of which explicitly deal with the price of Mg or life cycle analysis. It is true that Mg alloys can be expensive relative to competing alloys and polymers. Thus, their use must be justified in terms of lowered manufacturing cost (e.g. via part integration), lowered life cycle cost (e.g. lowered fuel consumption of a lighter vehicle), or a specific performance enhancement. During the workshop planning stages, it was decided that an explicit focus on these issues was outside the scope of the workshop objectives. For example, it is clear that political factors (including tariffs and other import controls) have a strong influence on the price of Mg alloy products, which can positively or negatively affect the prospects for more widespread application of Mg alloys. However, policy issues are not the immediate purview of the materials scientists and mechanical engineers who comprised the list of workshop participants. Two technical areas that have direct cost implications, which were not addressed, are magnesium extraction and recycling. On the other hand, we did address a number of technical barriers that have direct implications for the cost of using Mg alloys. For example:
Developing a better ability to predict macro/microstructure which results from the die casting processes would improve properties and foundry yields. This would enable the foundries to improve their margins or to lower the price for the end-user.
Exploring low cost methods of primary conversion, e.g. strip casting of Mg alloy sheet is also fruitful, particularly if it can be partnered with low-cost methods of sheet forming, such as a lower temperature forming.
Some of the alloy development strategies highlighted below target improving extrusion rates, which could affect the price of extrusions.
Finally, the entire subjects of coatings, corrosion, fatigue, and fracture all have a strong impact upon the longer term cost of use.
The details of these, and many other, strategies are more fully described in each of the breakout discussion summaries below.