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Various paths of equal channel angular pressing (ECAP) and conventional post-deformation via forging and rolling were performed to improve the mechanical properties (particularly, the strength and hardness) of a copper-free silver alloy. The microstructure was investigated with optical and scanning electron microscopy. The primary grain size of approximately 130 μm was significantly refined to ultrafine-grained (UFG) conditions with mean grain sizes of 0.6 μm and 0.5 μm via ECAP and ECAP with forging and rolling, respectively. The remarkable improvement of the mechanical properties was confirmed via hardness measurements and tensile and compression tests. ECAP and subsequent forging and rolling increased the initial hardness and tensile yield strength by +234% and +355%, respectively. Furthermore, ECAP led to a much more homogeneous hardness distribution over the entire cross-sections of the bars. The thermal stability of the UFG material at room temperature, 100 °C, and 150 °C was maintained for at least 27 months, 1000 h and 4 h, respectively. Finally, the UFG state exhibited a better tarnishing resistance than the coarse-grained state. Thus, ECAP can overcome the most significant weaknesses of lean, silver-based alloys (i.e. poor mechanical and tarnishing properties), thereby creating opportunities for their wider use.

The commercial magnesium alloy EZ33A was processed by Equal Channel Angular Pressing (ECAP). Two different tools were used: a conventional one with two channels and one intersection (90°), and a so-called double ECAP (D-ECAP) tool with two intersections (90° and 120°). Four passes were conducted at temperatures subsequently lowered from 350 °C down to 240 °C using route Bc. The as-cast, pre-deformed material and both ECAP conditions were investigated. The microstructure was revealed by means of optical microscopy, scanning and transmission electron microscopy (SEM, TEM), and X-ray diffraction. Mechanical properties were studied by Vickers hardness measurements as well as by compressive and tensile tests. The microstructure investigations show a significant grain refinement as well as fragmentation and redistribution of the hard intermetallic (Mg,Zn)12RE phase by ECAP. This effect is even more pronounced in the material processed by D-ECAP where this phase is two times finer compared to the size after conventional ECAP. Additionally, small Zn-Zr particles of a few nanometers size within grains or subgrains were observed. Microstructure changes evoked by the ECAP processing significantly affect the mechanical properties. This is especially the case after 4 passes in the D-ECAP tool where hardness (90 HV2) is almost 70% higher than in the as-cast condition (54 HV2) and the tensile yield strength is enhanced by nearly 300% (82 MPa up to 327 MPa). Hence, the D-ECAP tool is more efficient than the conventional one in improving mechanical properties.

The scope of this paper was to examine the effects of the ECAP procedure on the machinability of aluminium (EN AW-6082) based on turning tests. The behaviour of the ECAP material was investigated and compared to the as-received (AR) material. Since limited information on the machinability of ECAP materials is available, it was necessary to conduct an evaluation on basis of the untreated material. For this purpose, a defined range of cutting parameters, which were raised based on recommendations of the tool manufacturer were used for the first experiments. In order to analyse the effects of ECAP on the machinability the following comparative criteria were pulled up: the quality of the machined surfaces, appearing forces and chips produced.

Enhancing the strength of Mg-based biodegradable alloys without decreasing their corrosion resistance is a major engineering challenge. In addition, the growing demand for effective reduction of infections and inflammation after implant placement motivates the design of alloys with appropriate compositions or coatings. One promising alloying element is silver, whose antibacterial effect has long been known. Therefore, a Mg–4% Ag alloy was selected for this study. The alloy was investigated under three conditions: as-cast, after T4 treatment, and after T4 treatment with subsequent equal-channel angular pressing (ECAP) using a newly developed double-ECAP die, which offers an equivalent strain per pass of 1.6. The first pass through the double-ECAP die was conducted at 370 °C and the second at 330 °C using route BC. The microstructure of the as-cast Mg–4% Ag consisted of large grains (several hundred microns) and a dendritic structure with micron-sized Mg54Ag17 precipitates. T4 heat treatment caused dissolution of the dendrites and formation of a solid solution without changing the grain size. Consequently, the ultimate compressive strength (UCS) was increased by approximately 30%, and the compressive strain at fracture reached approximately 23%. The compressive yield strength (CYS) remained nearly constant at approximately 30 MPa. Subsequent ECAP led to strong grain refinement (from 350 μm to 38 μm after one pass and 15 μm after two passes) and further increases in the CYS and UCS, to 45 and 300 MPa after the first pass and 62 and 325 MPa after the second pass, respectively. The as-cast alloy exhibited a very high degradation rate in a simulated body fluid at approximately 36 °C. The degradation rate of the alloy after T4 treatment was much lower. Subsequent ECAP had no significant effect on the degradation properties. Thus, it can be concluded that grain refinement has little effect on the degradation rate.

Cylindrical tubes made of commercially-pure titanium (CP-Ti) filled with various mandrels (metallic as well as non-metallic materials) were processed by Equal Channel Angular Pressing (ECAP). Different temperatures (500°C down to room temperature), routes (Bc, B120, C), tools and number of passes (1-6) were applied depending on the mandrel material. For reasons of comparison, solid bolts made of metallic mandrel materials were processed at the same ECAP conditions. The mechanical properties of as-received as well as ECAP tubes and core materials were characterised by hardness mappings (in order to reveal the homogeneity) and tensile tests. The results can be summarised as follows: i) It is feasible to process tubes by ECAP; ii) Using appropriate mandrels, tubes made of CP-Ti can be processed by ECAP at significantly lower temperatures, even at room temperature, as compared to solid bolts; iii) Mechanical properties of tubes and mandrel materials after ECAP are similar to or even better than those of their solid counterparts; iv) Tubes after ECAP at low temperatures show higher strength than what can be achieved in bulk material; v) Excellent homogeneity of microhardness is achieved at least when metallic mandrels and a sufficient number of ECAP passes are used.

The elemental alkali metals as well as the earth-alkaline metal barium undergo phase transitions from an ambient bcc structure to close-packed structures (fcc or hcp, respectively) in a largely varying pressure range from 4.5 GPa in Cs up to more than 50 GPa in Na. Little is known about the mechanisms of these pressure-induced phase transitions. In particular, it is an open question whether the {\mathrm {bcc}}\to {\mathrm {fcc}} and {\mathrm {bcc\to hcp}} transformations are related to similar phase transitions at ambient pressure and low temperatures which occur in Li and Na but are absent in the heavy alkali metals and in Ba. In the present work, we have adapted the Paris–Edinburgh pressure cell for neutron scattering studies on single crystals of Li and Ba. It was found that under carefully chosen experimental conditions almost hydrostatic loading of Li and Ba up to about 7 GPa is possible. We describe the experimental methods which have allowed us to overcome the technical difficulties and report the first results of elastic neutron scattering on Li and Ba and inelastic neutron scattering on Li.