Shape memory materials are a class of smart materials able to convert heat into mechanical strain (or strain into heat), by virtue of a martensitic phase transformation. Some brittle materials such as intermetallics and ceramics exhibit a martensitic transformation, but fail by cracking at low strains and after only several applied strain cycles. Here we show that such failure can be suppressed in normally brittle martensitic ceramics by providing a fine-scale structure with few crystal grains. Such oligocrystalline structures reduce internal mismatch stresses during the martensitic transformation, and lead to robust shape memory ceramics capable of many superelastic cycles to large strains; here we describe samples cycled up to 50 times, and samples which can show strains over 7%. Shape memory ceramics with these properties represent a new class of actuators or smart materials with a unique set of properties that include high energy output, high energy damping, and high temperature usage.One Sentence Summary: Fine-scale shape memory ceramics capable of many actuation cycles to strains up to 7%.Main Text: Shape memory materials are solid-state transducers, able to convert heat to strain and vice versa. They exhibit two unique properties: 1) the shape memory effect, which is the ability to transform to a "remembered" pre-defined shape upon the application of heat and 2) superelasticity, which is the ability to deform to large strains recoverably, while dissipating energy as heat. The underlying mechanism in crystalline shape memory materials is a thermoelastic martensitic transformation between two crystallographic phases that can be induced thermally (shape memory effect) or with the application of stress (superelasticity) (1, 2).The ability to transduce heat and strain renders shape memory materials useful in a wide variety of actuation, energy damping, and energy harvesting applications (3-7). To be of practical use, the material must be able to accommodate the extreme deviatoric strains associated with the

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New techniques in solid freeform fabrication (SFF) have prompted research into methods of manufacturing and controlling porosity. The strategy of this research is to integrate computer aided design (CAD) and the SFF technique of selective laser sintering (SLS) to fabricate porous polymeric matrix drug delivery devices (DDDs). This study focuses on the control of the porosity of a matrix by manipulating the SLS process parameters of laser beam power and scan speed. Methylene blue dye is used as a drug model to infiltrate the matrices via a degassing method; visual inspection of dye penetration into the matrices is carried out. Most notably, the laser power matrices show a two-stage penetration process. The matrices are sectioned along the XZ planes and viewed under scanning electron microscope (SEM). The morphologies of the samples reveal a general increase in channel widths as laser power decreases and scan speed increases. The fractional release profiles of the matrices are determined by allowing the dye to diffuse out in vitro within a controlled environment. The results show that laser power and scan speed matrices deliver the dye for 8-9 days and have an evenly distributed profile. Mercury porosimetry is used to analyse the porosity of the matrices. Laser power matrices show a linear relationship between porosity and variation in parameter values. However, the same relationship for scan speed matrices turns out to be rather inconsistent. Relationships between the SLS parameters and the experimental results are developed using the fractional release rate equation for the infinite slab porous matrix DDD as a basis for correlation.

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