•Microstructure refinement and homogeneity of the Mg alloy with LPSO phase were attained after SS plus ECAP.•The refined microstructure resulted in higher strength and better ductility.•The fine-grained alloy was easily rolled into a thin sheet without edge cracking and with high productivity.•The combination processing has a great potential in producing Mg alloys with excellent overall performance.A fine-grained Mg–1.8Gd–1Zn–0.1Zr (at.%) alloy with long-period stacking ordered (LPSO) phase was obtained via solid-solution(SS) treatment plus multi-pass equal-channel angular pressing(ECAP). The effects of post-ECAP rolling on microstructure change and deformation characteristic of the Mg alloy were investigated. The results showed that the fine-grained alloy after 16 ECAP passes at 658 K had a yield strength of 334.4 MPa with an elongation of 22.5%. Grain refinement with LPSO formation simultaneously improved the strength and ductility of the ECAPed alloy, indicating a good plastic formability. The ECAPed Mg sheet was easily rolled at 773 K from 1.5 mm to 0.24 mm in thickness without edge cracking. After rolling, the fine-grained Mg alloy exhibited higher tensile strength with appropriate elongation. The post-ECAP rolling has been successfully used in the high productivity of Mg thin sheet with good mechanical properties.

•A deformed surface layer with fine grains was formed in a low-carbon steel by SFPB.•The top surface layer contained many dislocations and micro-cracks.•The fine-grained surface layer had a higher corrosion rate in a 3.5% NaCl solution.•The SFPB improved the passivity and pitting corrosion resistance of the steel.A grain refined surface layer thicker than 15 μm was fabricated on a low-carbon steel by supersonic fine-particles bombarding (SFPB). The microstructure and electrochemical corrosion properties of the original and the SFPB treated (SFPB-ed) low-carbon steel were characterized by optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and corrosion tests. The results showed that the microstructure of the top surface layer was refined to fine grains with the grain size about 3 μm by SFPB. Dislocation tangles and dense dislocation cells about 500 nm in width were formed in the refined grains. Large amounts of micro-cracks were introduced into the surface layer of the SFPB-ed sample, which led to the increase of its surface roughness. The SFPB treatment accelerated the corrosion of the low-carbon steel in a neutral 3.5 wt.% NaCl solution. The surface layer of the SFPB-ed low-carbon steel was dissolved after a certain time of corrosion, which led to the decrease of its corrosion rate. In a saturated Ca(OH)2 solution with and without Cl−, the micro-cracks in the surface layer of the SFPB-ed sample did not degrade its passivity properties and pitting resistance, which was due to the superior re-passivation properties of the abundant crystalline defects in its surface layer, such as grain boundaries and dislocations.

Ultrafine-grained (UFG) Al-26 wt% Si alloy was obtained through multipass equal-channel angular pressing (EACP) procedure and subsequently tested in 3.5 wt% NaCl solution for the evaluation of electrochemical corrosion. The results show that the ECAPed alloy with increased number of pressing passes obtain lower mass-loss ratios, nobler Ecorr and Epit, lower Icorr values, and higher anode polarization. The improved corrosion resistance of the ECAPed alloy results from the homogeneous UFG structure with the breakage of brittle large primary silicon crystals, which contributes to a higher pitting resistance. The oxidation product with improved adhesion force and protection efficacy can be formed with greater ease on UFG alloys. It implies that grain refinement through severe-plastic-deformation can enhance anticorrosion behavior of hypereutectic Al–Si alloys, besides the well-known strengthening and toughening effects.

The recent development of high-strength magnesium alloys is focused on the role of the strengthening phases with a novel long-period stacking-ordered (LPSO) structure. This review detailed the main factors influencing the formation of LPSO phases, including alloying elements, preparation methods, and heat treatments. Furthermore, process control in structure types, formation and transformation behavior, strengthening and toughening mechanisms of the LPSO phase were discussed. Finally, the current problems and development trends of high-strength Mg-Zn-RE alloys were also put forward.

In this work, the mechanical properties of equal channel angular processing (ECAP)-processed fine- and coarse-grained Cu–11.42Al–0.35Be–0.18B shape memory alloys (wt.%) were evaluated using tensile testing. After eight passes of ECAP and subsequently quenching from 600 °C to RT, the mean grain diameter was refined from 227 μm to 42 μm with grain boundaries purified. The fine-grained alloy exhibited good mechanical properties with a high tensile strength (703 MPa) and featured deeper and closer dimples on its fracture surface. The micro cracks were more refined, and the cracks extension along the grain boundaries was improved in the fine-grained alloy. These changes can be attributed to improvement of martensite morphology, structural refinement and grain boundary purification.

AbstractA low-carbon anti-wear steel, multi-alloyed with Si-Cr-Mn-Al-Ni-Mo-(Nb, RE), was designed for vane pumps of ships. The novel cast steel after various heat treatments was characterized by microstructure observations and mechanical properties measurement in order to achieve an optimal process correlated with good abrasive resistance for a long marine service. Differential scanning calorimetry and hardness analyses deduced a complete austenitizing temperature of 1 000 °C, based on the alloying element homogenization and defective structure elimination without grain coarsening. An optimal austempering process (austenitized at 1 000 °C, quick cooled for holding at 350 °C for 1.5 h and then air-cooled to room temperature) produced a uniform mixture structure of fine carbide-free aciculate bainites and few lath martensites, resulting in the tensile strength increase of 34% and impact toughness increase of 50% compared with that of the as-cast steel. The abrasive wheel tests show that the austempered steel has good wear resistance with a mass-loss rate of 170 mg/(km·cm2) under applied load of 70 N in acidic slurry. The new grade steel (containing anti-corrosion elements of Cr and rare earth) can find wide application in marine engineering, with further enhanced comprehensive properties via melting process improvement.