Formation of W-Re Solid Solution by Mechanical Alloying

Progress of mechanical alloying (MA) during milling of W with Re, in a SPEX Mill was monitored by x-ray diffraction, scanning electron microscopy and transmission electron microscopy. XRD patterns showed continuous decrease in the intensity of Re peaks with increasing MA time. However the Re peaks continued to be present even after 18 ks of milling. 36 kiloseconds of milling showed complete dissolution of Re, as observed by the absence of Re peaks in association with W peak shift in accordance with the dissolution of Re in W. Chemical homogeneity and extensive reduction in particle size of the alloy could be established by microstructural and chemical analysis using SEM and TEM. Isothermal heat treatment of the mechanically alloyed sample at 1700 K for 4 hours did not show any decomposition of the alloy. A similar heat treatment of the blended elemental powder showed the formation of metastable phase formation, possibly at the boundary of dissimilar powder particles. After pressing and sintering of pellets, tests revealed some amount of alloy contamination by iron through milling.     

Phase transformations in the Ti-6Al-4V-H system

Thermohydrogen processing, a technique in which hydrogen is used as a temporary alloying element in titanium, allows enhanced microstructural control and improved mechanical properties. This paper provides an improved definition of the phase transformations taking place in the Ti-6Al-4V-hydrogen system, which should lead to increased application of the technique.     

Microstructure and properties of a new super-high-strength Al–Zn–Mg–Cu alloy C912

Using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the microstructure of a new super-high-strength Al–Zn–Mg–Cu alloy (C912) has been investigated. Compared with some other high-strength aluminum alloys, the C912 alloy exhibits higher strength and good stress-corrosion resistance and its specific strength is even higher than some Al–Li alloys. Its potential for use in the Chinese AE100 airplane is discussed.