- Tuesday, June 24
- Wednesday, June 25
- Thursday, June 26
- Friday, June 27
- Saturday, June 28

**Select Sessions: **

- Elart von Collani “Statistics as a general tool for all sciences.”
- Francesca Greselin “Measuring inequality at the time of the Great Divergence.”
- Ernest Fokoue “Recent Applications of Statistical Data Mining for Big Data Predictive Analysis.”
- Vladimir Kaishev “Probability and statistics in actuarial applications.”
- Galia Novikova “Data Mining for Software Development Quality Management.”
- Leda Minkova “Stochastic Models and Statistical Applications.”
- Krzysztof Podgorski “Non-Gaussian stochastic models: theory and applications.”
- Kristina Sendova “Risk measures, probability measures and mortality.”

Kettering University is organizing this international conference to celebrate the IYS 2013 and the 175th anniversary of the American Statistical Association.

The main focus of this conference will be on STATISTICAL METHODS & STUDIES OF HISTORICAL DATA.

Participants may use any data. Data on Flint—consisting of up to 100 years of demographic, health, labor, census and crime records will be summarized and made available to participants. Sessions will include presentations of the statistical achievements and perspectives, followed by several talks on current results.

]]>Over fifty years ago, C. S. Smith and C. Zener proposed that for grain growth in a random dispersion of rigid, immobile particles of radius *r*, the maximum attainable grain size *R* is given by R = a r/fb where *f* is the volume fraction of particles and *a* and* b* are constants [1]. Under the Smith-Zener assumptions, *a* = 4/3 and *b* = 1.

A number of subsequent investigators have proposed corrections to the Smith-Zener approach [2-10]. While these corrections modify *a* and *b*, *a* remains of order unity and* b* remains near one.

However, controversy about the validity of the Smith-Zener equation has continued for two reasons. First, experiments often do not find *b* = 1 [9,11]. Second, in the 1980s, computer simulations of particle pinned grain growth in three dimensions found *b* = 1/3 [12-14].

The inconsistency in experimental results is due to a variety of deficiencies in experimental design, including initial grain size larger than the predicted pinned size, particles which move or coarsen, solute or liquid present on the grain boundaries, and mechanical driving force for coarsening. A discussion of these issues is found in [15-18].

By examining the structures formed at particle/boundary intersections, Miodownik *et al*. found that previous Monte Carlo Potts model computer simulations of particle pinning were flawed as well [19]. Prior simulations were performed under thermodynamic conditions where particles can induce artificial facetting of grain boundaries along simulation lattice planes. This facetting removes boundary curvature and ultimately stops grain growth. When sufficient thermal energy is imparted to the system, the boundaries roughen, facets disappear, and the particle/boundary structure takes on the catenoid geometry predicted by Smith and Zener. Under these conditions, simulations of boundary motion in an idealized grain structure indicate a pinning exponent *b* ∼ 1, in agreement with the Smith-Zener theory [20].

While the idealized geometry examined by Miodownik *et al*. does not include the full topological complexity of a real grain microstructure, computational limitations have prevented pinning simulations on polycrystals. In this paper, we present the first results of correct particle pinning simulations on realistic, three-dimensional polycrystals.

The microstructures of metallic and ceramic materials are known to be strongly influenced by the presence of second phase particles. Second phase particles may pin grain boundaries and hence may be used to limit grain size (l-4). When particles are mobile, grain boundary/particle interactions typically lead to an even higher density of grain boundary/particle intersections than with static particles. The present paper addresses the influence of mobile particles on grain size evolution in polycrystalline materials.

Particle mobility varies sensitively with particle size r (as l/r3 or l/r4) and temperature (in an Arrhenius manner) (5,6). Thus the effects of non-zero particle mobility on gram structure should be most easily observed at elevated temperatures and for small particles. Interactions between moving gram boundaries and mobile impurities has received considerable attention (e.g., (7-9)). These studies have shown that when the driving force on the gram boundary is small (or the impurity mobility is large), impurities diffuse to the moving boundary, and the boundary impurities move together, in a highly correlated manner. In this case, the boundary velocity will be small. But if the driving force on the boundary is large, or the impurity mobility is low, the boundary can escape the impurities and move at a much higher velocity In some cases, these two regimes are not easily distinguished.

In the present study, we employ a Monte Carlo simulation procedure to study grain growth in the presence of diffusing particles. This simulation procedure has been used to study a wide variety of grain growth phenomena (2-4,10-13). We examine the temporal evolution of the grain size and microstructure, and the influence of particle fraction, and temperature. The results are analyzed in terms of the relationship between the boundary driving force and the steady state boundary velocity.

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