Wire arc additive manufacturing (WAAM) technology was used to produce samples of a 2.25Cr1Mo0.25V heat-resistant steel. The phase composition, microstructure, and crystal structure of the investigated material in the as-cladded state and postcladding heat-treated (705°C × 1 h) state were analysed by optical emission spectrometry (OES), optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The properties of the investigated material in the as-cladded state and postcladding heat-treated (705°C × 1 h) state were determined by a microhardness tester, mechanical properties tester, and Charpy impact tester. Through a study of the microstructure and properties, it is found that the investigated material produced by WAAM exhibits good forming quality and excellent metallurgical bonding properties, and no obvious defects are found. The microstructure consists mainly of Bg (granular bainite) and troostite precipitated at the grain boundaries. The results from high-resolution transmission electron microscopy observations show that the crystal structures of the 2.25Cr1Mo0.25V heat-resistant steel samples produced by WAAM in the as-cladded condition have many defects, such as dislocations and martensite-austenite (M-A) constituents, and their grain edges are sharp. There is a dramatic decrease in the dislocations in the 2.25Cr1Mo0.25V heat-resistant steel samples produced by the WAAM condition after the postcladding heat treatment (705°C × 1 h), and the grains become smooth. The distribution of the microhardness in the longitudinal and transverse cross sections of the samples is very uniform. The average longitudinal and transverse microhardness of the samples in the as-cladded state is 310 HV0.5 and 324 HV0.5, respectively. The average longitudinal and transverse microhardness of the samples after post-cladding heat treatment is 227 HV0.5 and 229 HV0.5, respectively. The yield strength of the samples without a postcladding heat treatment is 743 MPa, the tensile strength is 951 MPa, the elongation is 10%, and the Charpy impact value at -20°C is 15 J. After the postcladding heat treatment, the yield strength, tensile strength, elongation, and Charpy impact value of the samples are 611 MPa, 704 MPa, 14.5%, and 70 J, respectively.

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The non-heat-treated, die-cast aluminum alloy samples were prepared meticulously via die-casting technology. The crystal structure, microstructure, and phase composition of the samples were comprehensively studied through electron backscatter diffraction (EBSD), metallographic microscopy, spectrometer, and transmission electron microscopy (TEM). The microhardness and tensile properties of the samples were tested. The die-cast samples were found to have desirable properties by studying the structure and performance of the samples. There were no defects, such as pores, cold partitions, or surface cracks, found. The metallographic structure of the samples was mainly α-Al, and various phases were distributed at the grain boundaries. Before heat treating, α-Al grains were mainly equiaxed with a great number of second phase particles at the grain boundaries. After heat treating, the α-Al grains were massive and coarsened, and the second phase grains were refined and uniformly distributed, compared with those before the heat treating. The EBSD results showed that the grain boundary Si particles were solid solution decomposed after heat treatment. The particles became smaller, and their distribution was more uniform. Transmission electron microscopy found that there were nano-scale Al-Mn, Al-Cu, and Cu phases dispersed in the samples. The average microhardness of the samples before heat treating was 114 HV0.1, while, after the heat treating, the microhardness reached 121 HV0.1. The mechanical features of the samples were tremendous, and the obtained die-cast aluminum alloy had non-heat-treatment performance, which was greater than the ordinary die-cast aluminum alloys with a similar composition. The tensile strength of the aluminum alloys reached up to 310 MPa before heat treatment.

Inconel 625 superalloy samples were fabricated using wire arc additive manufacturing (WAAM). The phase composition, microstructure, anti-corrosion, and mechanical properties of the Inconel 625 WAAM samples were analyzed. The microstructure of the Inconel 625 WAAM alloy showed good forming quality, no defects, and good metallurgical bonding within the specimens. The metallographic structure exhibited primarily γ-Ni and granular precipitated phases; the average microhardness of the transverse and longitudinal cross-sections of the sample was 243.5 and 243.3 HV0.1, respectively. Yield and tensile strength as well as elongation, decrease in area, and the room-temperature impact values of this alloy were equal to 450 and 736 MPa, 38% and 52%, and 152 J, respectively. The intergranular corrosion test results indicated that the average corrosion rate of the sample is 0.609 mm/year, indicating excellent resistance to intergranular corrosion.

The initial yield surface of a superplastic material was investigated by using a combined loading of axial force and torque. The thin-walled tubular specimen made of Zn-22 wt.%A1 alloy was used in the experimental part of this study. Tests were carried out at room temperature (293 K) and at elevated temperature (523 K). The experimental results show that the malerial tesled did not deform superplastically at 293 K exhibiting a yield surface that can be described by the second invariant of stress deviator (by Mises' criterion). On the other hand, the material was found to deform superplastically at the higher temperature of 523 K with a yield surface more complex compared to that observed at 293 K. This difference may be attributed to the difference in major deformation mechanism at two applied temperatures; that is, the slip within the grains at 293 K and the grain boundary sliding at 523 K.