Water-induced reversible dissolution/reorganization transformations of Cu(Ⅱ)-K(I) heterometallic coordination polymers

Three new heterometallic coordination compounds, namely, [KCu（I3）（L）2（H2O）2]n （1）, [KCu（I3）（L）2（H20）]n （2） and [CIIK4（I3）z（L＇）4]n （3）, were prepared and characterized （HL=5-methylpyrazine-2-carboxylic acid, HL＇=p-tolylacetic acid）. Structural studies revealed that 1 and 2 exhibit 3D frameworks with rectangular channels occupied by triiodide ions. Both compounds can be symbolized as a 5-connected net with pcu topology. In compound 3, a one-dimensional polyhedral chain is connected by hexanuclear mask like clusters [Cu2K408]. These chains are further linked each other via rare （1,1,3,3）-triiodide ion-bridging units to generate a 3D （4,5,6）-connected net with the point symbol of { 12}2{4·12^2}4{4^6}{4^8·62}4{49.66}4. It is noteworthy that water-induced reversible dissolution/reorganization processes occur between 1/2 and [Cu（L）2（HzO）],＇3nH20. The thermal and photoluminescence properties of compounds 1, 2, and 3 were investigated as well.

Effect of martensitic transformation on nano/ultrafine-grained structure in 304 austenitic stainless steel

304 austenitic stainless steel was cold rolled in the range of 20%-80%reductions and then annealed at 700-900°C for 60 sto obtain nano/ultrafine-grained（NG/UFG）structure.Transmission electron microscopy,electron backscatter diffraction and X-ray diffraction were used to characterize the resulting microstructures.The results showed that with the increase of cold reduction,the content of martensite was increased.The steel performed work hardening during cold-working owing to the occurrence of strain induced martensite which nucleated in single shear bands.Further rolling broke up the lath-type martensite into dislocation-cell type martensite because of the formation of slip bands.Samples annealed at 800-960°C for 60 swere of NG/UFG structure with different percentage of nanocrystalline（60-100 nm）and ultrafine（100-500 nm）grains,submicron size（500-1000 nm）grains and micron size（〉1000 nm）grains.The value of the Gibbs free energy exhibited that the reversion mechanism of the reversion process was shear controlled by the annealing temperature.For a certain annealing time during the reversion process,austenite nucleated first on dislocation-cell type martensite and the grains grew up subsequently and eventually to be micrometer/submicrometer grains,while the nucleation of austenite on lath-type martensite occurred later resulting in nanocrystalline/ultrafine grains.The existence of the NG/UFG structure led to a higher strength and toughness during tensile test.