[en] Based on the airborne radioactive and aeromagnetic data of the Zhongchuan rock mass group in West Qinling Mountains, the boundary of the rock mass is identified with the boundary enhancement technique, and the characteristics of its airborne radioactive anomalies and aeromagnetic anomalies are analyzed referred to the geological condition. This paper compared the aeromagnetic and airborne radioactive characteristics, a deep research on the uranium deposits and gold deposits have been done using the multiple parameters technique. Besides, this paper summarized the similarities and differences of the uranium deposits and gold deposits in the spatial and temporal distribution and aeromagnetic and airborne radioactive characteristics. Overall, the favorable location of uranium prospecting in the area of the Zhongchuan rock mass is where the uranium increment, the uranium variance and the uranium content all have higher values, besides magnetic field gradient zone is obvious, while the favorable location of gold prospecting is where the potassium increment, potassium variance and thorium variance all have higher values, besides the negative magnetic field or gradient zone of the aeromagnetic ΔT residual anomalies is obvious. Finally, the prospecting sites of gold deposit and uranium deposit is delineate in the Zhongchuan rock mass group, it has favorable directions for further ore-prospecting of this area. (authors)

[en] This paper briefly presented the basic theory and data interpretation of airborne electromagnetic method. By analyzing the application effect of the method with some uranium and polymetallic mineral exploration cases, the airborne electromagnetic technology was discussed on the application prospect for the explorations of deep uranium deposit. (authors)

[en] Elemental powder metallurgy is an effective way to improve the ductility and strength of nanostructured TiAl alloys. However, the high ductility of Al largely restricts the application of elemental powder metallurgy. Here we demonstrate a novel avenue in fabricating nanostructured Ti-45Al-8Nb alloys by cryomilling (CM) and Spark Plasma Sintering (SPS) from elemental powder metallurgy. Our work reveals that CM not only prevents the Ti/Al/Nb powder mixture from cold welding, but also makes the resultant powder homogeneous with an average particle size of 217 nm. The nano-powders were sintered by SPS at 900, 1000 and 1100 °C, forming ultrafine grained (UFG) equiaxed near-γ and lamellar structures. Particularly, as a result of grain refinement strengthening, the specimen sintered at 1000 °C shows excellent mechanical properties, with the compression yield strength, fracture strength and plastic strain as 1575 MPa, 2627 MPa and 23.5%, respectively at room temperature; and 955 MPa, 1041 MPa and 38.4%, respectively at 850 °C. This work demonstrates the superiority of the combined CM-SPS in fabricating nanostructured Ti-45Al-8Nb alloys with enhanced mechanical properties, which is considered as highly potential in exploring high-performance TiAl alloys.

[en] The high solidification rate of selective laser melting (SLM) induces a nonequilibrium microstructure in as-fabricated Ti alloys. Herein, a metastable β Ti-5Al-5Mo-5V-3Cr-1Zr alloy is successfully fabricated by SLM on a preheated substrate at 700 °C. The effects of preheating temperature on microstructure and mechanical properties of as-fabricated specimens is systematically studied. The phase identification and electron microscopic results demonstrate that the 700 °C preheating temperature enables the transformation of metastable β structure into an α + β structure with massive amounts of nanosized α precipitates. Consequently, the SLM-fabricated specimen after preheating process possesses higher ultimate tensile strength and hardness at 1440 MPa and 8.24 GPa, respectively. This work shows an alternative for SLM to tackle nonequilibrium microstructure and to increase the strength of metastable Ti alloys by introducing high temperature preheating. (© 2021 Wiley‐VCH GmbH)

[en] Highlights: • Ti55531 with metastable β structure was fabricated by SLM. • Three conventional heat treatments were used to tailor the metastable β structure. • Heat treatment can enhance the strength of SLMed Ti55531. -- Abstract: The unique solidification character of selective laser melting (SLM) can result in non-equilibrium microstructure and correspondingly unreliable mechanical properties in as-built Ti-alloy components. As a classical microstructure optimization method, heat treatment is promising in tailoring the microstructure and enhancing the mechanical properties of SLM-built Ti-alloys. This study aimed to increase the strength of metastable β structure of SLM-fabricated near β Ti-5Al-5Mo-5 V-3Cr-1Zr (Ti55531) alloy via heat treatment. Three conventional heat treatments, including solution in β phase region and aging (β-STA), triplex heat treatment, and solution in α + β phase region and aging (αβ-STA) were carried out to tailor the metastable β structure, and the transformed β, bi-lamellar and bimodal structures were formed respectively. Tensile tests were performed on horizontal and vertical planes in order to evaluate the anisotropy and the relationship between microstructures and mechanical properties. It was found that the strength and ductility were influenced by the intragranular α precipitates and the intergranular α continuity along β grain boundary, respectively. The anisotropic tensile behavior in these heat treated samples was affected by the β grain morphology. This work demonstrated that SLM-fabricated metastable β Ti-alloy had a strong heat treatability, which can provide different heat treated microstructures and mechanical property.