The study discusses the oxidation induration and swelling behavior of chromium-bearing vanadium titanomagnetite pellets (CVTP) with V 2 O 5 additions, and the reduction swelling index (RSI) and compressive strength (CS) of reduced CVTP were investigated with simulated coke oven gas (COG) injection into the blast furnace (BF). The results show that the CS of CVTP decreases and the porosity of CVTP increases with increasing V 2 O 5 additions. The proportion of microsize pore size distribution of CVTP between 0 to 5 μm decreases notably while the pore size distribution between 5 to 30 μm increases with increasing V 2 O 5 additions. The V 2 O 5 mainly exists in the form of V 2 Ti 3 O 9 and V 1.93 Cr 0.07 O 3 in CVTP and V 2 TiO 5 in reduced CVTP. The V-bearing spinels on the grain boundaries with fragmentized and prismatic structure restrain the CS of CVTP. The CS of reduced CVTP decreases and RSI increases with increasing V 2 O 5 additions. The V 2 O 5 addition facilitates the aggregation and diffusion of metallic iron particles, and the shape of the metallic iron whiskers transform round dot to prismatic. The pores and intervals enlarge, and thickness of lamellar crystals thickens gradually with increasing V 2 O 5 additions. The study could supply the theoretical and technical basis for the utilization of CVTP and other V-bearing ores with COG recyclable technology. KEY WORDS: V 2 O 5 ; oxidation induration; reduction swelling index; coke oven gas; chromium-bearing vanadium titanomagnetite pellets.

Microstructures and Vickers microhardness in AZ91 magnesium alloys without and with 1mass%Y addition fabricated by casting were investigated. Vickers microhardness increases with adding 1%Y. Microstructure in AZ91 without Y addition was analyzed to contain mainly α-Mg and Mg17Al12by X-ray diffraction. Microstructural observations with optical, scanning and transmission electron microscopes show that microstructure consists of α-Mg dendrite, non-equilibrium eutectic Mg17Al12and lamellar Mg17Al12. The non-equilibrium eutectic Mg17Al12exists between α-Mg dendrites. The lamellar Mg17Al12forms near the edge of the α-Mg dendrite arm. The lamellar Mg17Al12has Burgers orientation relationship for α-Mg matrix. It suggests that the lamellar Mg17Al12precipitates from Al-supersaturated region within α-Mg dendrite. Addition of Y to AZ91 hardly changes dendrite arm spacing, but decreases a size of region, where longitudinal directions of primary dendrite arms are almost parallel or a single dendrite exists. Y-addition increases nucleation site for dendrite, namely makes the unidirectionally-solidified region fine, resulting in increase in hardness.