Rare earth market quotation in China: neodymium oxide and praseodymium neodymium oxide prices decline slightly while holmium oxide and dysprosium oxide prices edge higher on April 23, 2023. 

China molybdenum price has moved up significantly on April 23, 2023. For example, molybdenum oxide price has returned to above 3,000 yuan/mtu, and the prices of ferromolybdenum and ammonium heptamolybdate have also broken through the 200,000 yuan/ton mark again. The actual transaction volume also increased slightly.

Researchers have investigated the oxidation behavior of W-Cr-Nb ternary alloys and W-Cr-Zr ternary alloys. Suresh et al. reported the oxidation behavior of W-Cr-Nb ternary alloys at 1000°C for 15 hours (30 cycles). The microstructure results of different W-Cr-Nb alloys showed that W-Cr-Nb ternary alloys have high density and small amount of porosity, and their true density is 97.5-98.5% of their theoretical density.W-Cr-Nb ternary alloys are mainly composed of W-rich solid solution (WSS) and Cr₂Nb phases.

Calvo et al. prepared W-Cr-Y ternary alloys with Cr content of 8 and 10 wt% and Y content of 0.3, 0.5 and 1 wt% by HIP technique and studied their oxidation behavior. The microstructure pictures of the HIPed alloy surface showed a fine surface structure and homogeneous composition. EDS analysis showed that most of the bright gray areas were Cr-rich phases, while the dark gray discontinuous areas were W-rich phase. The W-Cr-Y alloy has a lower grain size of 0.5-1 µm compared to the W-15Cr alloy. This suggests that the addition of Y can act as a grain growth inhibitor. In addition, nanoscale black Y₂O₃ particles were observed at the grain boundaries, which were caused by the decomposition of unstable oxides during the HIPing process.

Garcia et al. produced W-Cr-Ti ternary alloys—WCr12Ti2.5 (wt%) alloys by MA and hot isostatic pressing (HIP) techniques and investigated the oxidation behavior of the alloy. The results showed that the Δ m/S of the WCr₁₂Ti_2.5 alloy was 1.25 × 10^-2 to 4 × 10^-2 times higher than that of the W-Cr alloy during the first 15 h of oxidation at 800 °C. In addition, the former is 2 × 10^-2 to 5 × 10^-2 times higher than the latter for the first 5 h of oxidation at 1000 °C. With increasing oxidation time, the oxide layer of the WCr₁₂Ti_2.5 alloy becomes thicker and its porosity gradually increases. In addition, the oxidized alloy has a similar cross-sectional structure, consisting of black, dark gray and light gray phases from inside to outside, respectively.

Cr is a traditional antioxidant beneficial element that is widely used in the oxidation protection process of metals. In addition, it has the same body-centered cubic structure as the tungsten element. Therefore, the oxidation behavior of W-Cr binary alloys has been studied extensively by related scholars. Telu et al. prepared W_0.7Cr_0.3, W_0.5Cr_0.5 and W_0.4Cr_0.6 alloys by mechanical alloying (MA) and observed that the two phases (Wss, Crss) have significantly different brightness.

The W-Si ternary alloys own a longer oxidation life than W-Si binary alloys. The oxidation behavior of different ternary alloys is significantly lower compared to those of pure W and WSi13 alloys. In the temperature range of 600-1000°C, the oxidation rate of WSi₁₃Zr₁₃ alloy is only 0.16-0.27 times that of WSi₁₃ alloy. the oxidation rate of W-Si-Cr alloy is lower than that of WSi₉Y₁₃ alloy, while the oxidation rates of WSi₈Cr₁₂ and WSi₁₂Cr₇ alloys at 1000°C are only 0.25 and 0.023 times that of WSi₉Y₁₃ alloy, respectively. 0.25 and 0.023 times, respectively.

W-Si binary alloys are mainly composed of Si and W-Si compounds. During oxidation behavior of W-Si alloys, the surface of the alloy is readily oxidized, producing a dense and continuous protective film of SiO₂. It will act as a diffusion barrier and delay further diffusion of oxygen into the alloy.

Analysis of latest tungsten market from Chinatungsten Online

The ferro tungsten and tungsten carbide powder prices in the Chinese market stabilize on April 20, 2023 when most market participants are waiting for the release of new guide prices from listed tungsten companies. 

This week, China rare earth prices fell first and then rose. At the beginning of the week, due to the slightly increased supply of rare earth raw materials, the strong sentiment of downstream users to suppress prices and the weak demand, the prices of praseodymium, neodymium, dysprosium, terbium and NdFeB roughs fell.