The enhancement of the mechanical properties of TiAl alloys through the introduction of a second-phase reinforcement is highly essential. In this paper, using graphite powder as a carbon source, the Ti₂AlC phase is introduced to improve the compression and friction properties of the TiAl alloy. Concurrently, the effects of graphite powder additions on the microstructure and room-temperature mechanical properties of Ti-45Al-8Nb-xC (mass%) alloys are investigated. The results show that as the volume fraction of Ti₂AlC and the interdendritic γ phase increases, the length–diameter ratio of the Ti₂AlC phase decreases with increases in the graphite powder addition. The addition of graphite powder results in a refining effect on the grain size and lamellar spacing of the Ti-45Al-8Nb-xC (mass%) alloys. As the graphite powder content increases from 0 to 0.9 mass%, the microhardness increases from 557 HV to 647 HV. The room-temperature compressive strength and strain of the Ti-45Al-8Nb-xC (mass%) alloys first increase and then decrease with the addition of graphite powder. Specifically, when the content of graphite powder is 0.6 mass%, the alloy exhibits a maximum compressive strength and strain of 1652 MPa and 22.2%, respectively. Compared with the alloy without the graphite powder addition, the compressive strength and strain are improved by 37.7% and 62.1%, respectively. The wear resistance of the alloys is improved through the addition of graphite powder and the wear rate decreases from 5.062 to 2.125 × 10⁻⁴ mm³·N⁻¹·m⁻¹ as the content of graphite powder increases from 0 to 0.9 mass%.

To investigate the effect of surface roughness on the fretting wear behavior of the Inconel 718 alloy, specimens fabricated by selective laser melting (SLM) were polished using SiC abrasive papers to obtain different surface roughness levels. Ball-on-flat tangential fretting tests were conducted under a normal load of 50 N, displacement amplitudes of 50 and 100 µm, and a total of 10⁴ cycles. The results reveal that all test conditions fall within the gross slip regime (GSR). The coefficient of friction was not significantly affected by surface roughness, while the energy dissipation per cycle exhibited a decreasing trend with decreasing roughness. The high-roughness surface (R_a = 0.80 µm) exhibited severe stress concentration, leading to asperity fracture and fatigue delamination. The medium-roughness specimen (R_a = 0.43 µm) developed a dense third-body layer, showing a synergistic mechanism of abrasive and fatigue wear. The low-roughness specimen (R_a = 0.07 µm) maintained a stable contact interface with sufficient debris evacuation, dominated by adhesive and abrasive wear. At a displacement amplitude of D = 100 µm, the wear depth reached −6 µm, indicating the largest material removal and the most severe damage.

Ti-45Al-8Nb alloy is widely utilized in the lightweight design of the aerospace field because of its excellent properties. In order to make full use of this alloy, it is important to carry out relevant research, such as into the joining process of Ti-45Al-8Nb alloy. In this work, Ti-45Al-8Nb alloys were successfully connected by a TiZrCuNi amorphous interlayer, which was fabricated using the rapid solidification method. Ti-45Al-8Nb joints were composed of two zones. The typical microstructure of a Ti-45Al-8Nb joint was Ti-45Al-8Nb/AlCuTi + Ti₃Al/(Ti, Zr)(Cu, Ni) + (Ti, Zr)₂(Cu, Ni)/Ti₃Al + AlCuTi/Ti-45Al-8Nb. The diffusion of elements between the interlayer and the substrate was enhanced by increasing the brazing temperature, which resulted in an increase in the thickness of the interfacial reaction layer. The maximum shear strength was 171.2 MPa, which was obtained at 930 °C. The typical cleavage fracture was found in all of the Ti-45Al-8Nb joints. The mechanical properties of the joint were compromised at high brazing temperature due to the presence of excessive (Ti, Zr)₂(Cu, Ni) phase and coarse Ti₃Al phase, both of which are inherently brittle and harmful to the shear strength of the obtained joint.

The quality of metal products plays a crucial role in determining their overall performance, reliability and safety. Therefore, timely and effective detection of metal surface defects is of great significance. For this purpose, we present a densely connected network with multi-attention for metal surface defect segmentation, called MADC-Net. Firstly, we selected ResNet50 as the encoder due to its robust performance. To capture richer contextual information from the defect feature map, we designed a densely connected network and incorporated the multi-attention of a CESConv module, an efficient channel attention module (ECAM), and a simple attention module (SimAM) into the decoder. In addition, in the final stage of the decoder, we introduced a reconfigurable efficient attention module (REAM) to reduce redundant calculations and enhance the detection of complex defect structures. Finally, a series of comprehensive comparative and ablation experiments were conducted on the publicly available SD-saliency-900 dataset and our self-constructed Bearing dataset, all of which validated that our proposed method was effective and reliable in defect segmentation. Specifically, the Dice and Jaccard scores for the SD-saliency-900 dataset were 88.82% and 79.96%. In comparison, for the Bearing dataset, the Dice score was 78.24% and the Jaccard score was 64.74%.