Re-dissolution and re-precipitation behavior of nano-precipitated phase in Al-Cu-Mg alloy subjected to rapid cold stamping

High-resolution transmission electron microscopy(TEM),X-ray diffractometry(XRD),energy dispersive spectroscopy(EDS)and hardness test were used to study the re-dissolution and re-precipitation behavior of nano-precipitates of the spray-formed fine-grained Al-Cu-Mg alloy during rapid cold stamping deformation.Results show that the extruded Al-Cu-Mg alloy undergoes obvious re-dissolution and re-precipitation during the rapid cold-stamping deformation process.The plasticθ′phase has a slower re-dissolution rate than the brittle S′phase.The long strip-shaped S′phases and the acicularθ′phases in Al-Cu-Mg alloy after three passes of cold stamping basically re-dissolved to form a supersaturated solid solution.A large number of fine granular balanceθphases precipitate after four passes of rapid cold-stamping deformation.Rapid cold stamping deformation causes the S′phase andθ′phase to break and promote the nano-precipitate phases to re-dissolve.The high distortion free energy of the matrix promotes the precipitation of the equilibriumθphase,and the hardness of the alloy obviously increases from HB 55 to HB 125 after the rapid cold stamping process.

Effect of precipitation/re-dissolution processes from the supersaturated solution on the intestinal absorption of poorly water-soluble drugs

As one of the possible technologies to improve the oral absorption of poorly water-soluble drugs, supersaturable formulation, which enables to dissolve the drug to the higher concentration than their equilibrium solubility, is now attracting the attention (1)This include salt-formation, soliddispersion, co-crystallization or the use of amorphous form.Since supersaturation is a thermodynamically metastable state,supersaturated solution has a high potential to precipitate. Some pharmaceutical excipients.

Phase-field simulation of re-dissolution of γ’phase in Ni-Al alloy by continuous and second-order aging treatment

The morphology and kinetics evolution of the γ’(Ni3 Al)phase during re-dissolution are studied in Ni-15 at% Al alloy,the changes of volume fraction and average particle radius of theγ’phase were clarified with phasefield simulation.During isothermal aging,the interdistance of the neighboringγ’phase affects the interface concentration gradient of Al,which dominates the growth or redissolution of the γ’phase particle.After isothermal aging at 700 K,the alloy is continuously heated to 900 K with different heating rates,the re-dissolution lag happens,meaning the coalescence coarsening of adjacent γ’phase particles still proceeds at the initial heating stage.The predissolution of γ’phase with cubic shape is re-dissolved firstly at the edges and corners,in continuous heating to 900 K or by second-order aging from 700 to 900 K.Different from continuous heating,in the second-order aging process,the connected particles with band shape are broken initially by re-dissolving.At different heating rates,the similar dynamic relationships are abstracted for the volume fraction and the heating rates,and the average particle radius and the heating rates.