Synergistic Effect of La and TiB2 Particles on Grain Refinement in Aluminum Alloy

Synergistic effect of TiB2 (in form of Al-5Ti-1B) and La on grain refining results in Al-2Cu alloy was investigated. α-Al grains are significantly refined by Al-5Ti-1B. When trace La is added to the melt, further refinement is exhibited. Average grain size and nucleation undercooling of α-Al reduce first and then almost remain unchanged with La addition. Satisfactory grain refining result achieves when La addition level reaches 600 ppm. When more than 600 ppm La is added to the melt, La-rich particles form and the effect of solute La left in matrix on the microstructure almost no longer changes. Theoretical calculation results demonstrate that solute La segregates to Al melt/TiB2 particles interface along with Ti and Cu prior to α-Al nucleation and the synergistic effect of La and TiB2 particles on grain refinement mainly attributes to the enhancement in the potency of TiB2 particles to heterogeneously nucleate α-Al by trace La addition.

Surprising coercivity increment of sintered Ce–Fe–B magnets: Ce partly substituted by La

Aiming at refining the unideal microstructure and magnetic performance of sintered Ce–Fe–B magnets, La was introduced into the alloy. The role of La addition on the microstructure and magnetic properties revolution of Ce–Fe–B magnet was investigated in this study. The results suggested that La substitution could obstacle the phase structure deterioration during sintering process and maintained high 2:14:1 phase proportion. Meanwhile, uniform grain size and continuous RE-rich grain boundary phase appeared with La addition, which could be attributed to the segregation behaviors of La element and enhanced oxidation resistance with more 2:14:1 phase. The coercivity showed noteworthy increase from 2.93 kOe to 4.78 kOe under the synergetic effect of maintained 2:14:1 phase proportion, uniform RE2Fe[Formula: see text]B grain and even RE-rich phase distribution. This work indicated that La could act as a useful additive to obtain the cost-effective magnetic materials with moderate performance.

The Impact of Lanthanum and Zeolite Structure on Hydrocarbon Storage

Hydrocarbon traps can be used to bridge the temperature gap from the cold start of a vehicle until the exhaust after-treatment catalyst has reached its operating temperature. In this work, we investigate the effect of zeolite structure (ZSM-5, BEA, SSZ-13) and the effect of La addition to H-BEA and H-ZSM-5 on the hydrocarbon storage capacity by temperature-programmed desorption and DRIFT spectroscopy. The results show that the presence of La has a significant effect on the adsorption characteristics of toluene on the BEA-supported La materials. A low loading of La onto zeolite BEA (2% La-BEA) improves not only the toluene adsorption capacity but also the retention of toluene. However, a higher loading of La results in a decrease in the adsorbed amount of toluene, which likely is due to partial blocking of the pore of the support. High loadings of La in BEA result in a contraction of the unit cell of the zeolite as evidenced by XRD. A synergetic effect of having simultaneously different types of hydrocarbons (toluene, propene, and propane) in the feed is found for samples containing ZSM-5, where the desorption temperature of propane increases, and the quantity that desorbed increases by a factor of four. This is found to be due to the interaction between toluene and propane inside the structure of the zeolite.