Poor mechanical strength and creep resistance limit the orthopedic application of biodegradable Zinc (Zn). In present work, cerium (Ce) was alloyed with Zn using laser additive manufacturing technique. As one kind of rare earth element, Ce possessed high surface activity, which effectively interrupted the grain growth and caused the formation of stable intermetallics, thus contributing to grain refinement strengthening and precipitate strengthening. More significantly, Ce alloying activated more pyramidal slip by means of reducing the critical resolved shear stress during plastic deformation, and resultantly formed the sessile dislocations, which caused the accumulated strain hardening and improved the creep resistance. As a result, Zn-Ce alloy exhibited a considerably improved ultimate tensile strength of 247.4 ± 7.2 MPa, and a reduced creep rate of 1.68 × 10−7 s−1. Moreover, it exhibited strong antibacterial activity, as well as favorable cytocompatibility and hemocompatibility. All these results demonstrated the great potential of Zn-Ce alloy as a candidate for bone repair application.

Rare earth improves strength and creep resistance of additively manufactured Zn implants

Refinement of as-cast structures is one of the most effective approaches to improve mechanical properties, formability, and surface quality of steel castings and ingots. In the past few decades, addition of rare earths (REs), lanthanum and cerium in particular, has been considered as a practical and effective method to refine the as-cast steels. However, previous reports contained inconsistent, sometime even contradictory, results. This review summaries the major published results on investigation of the roles of lanthanum or/and cerium in various steels, provides reviews on the similarity and difference of previous studies, and clarifies the inconsistent results. The proposed mechanisms of grain refinement by the addition of lanthanum or/and cerium are also reviewed. It is concluded that the grain refinement of steels by RE additions is attributed to either heterogeneous nucleation on the in-situ formed RE inclusions, a solute effect, or the combined effect of both. The models/theories for evaluation of heterogeneous nucleation potency and for solute effect on grain refinement of cast metals are also briefly summarized.

Roles of Lanthanum and Cerium in Grain Refinement of Steels during Solidification

Blast furnace hot metal temperature and silicon content prediction using soft sensor based on fuzzy C-means and exogenous nonlinear autoregressive models

Very high cycle fatigue behavior of bearing steel with rare earth addition

Study on transverse-longitudinal fatigue properties and their effective-inclusion-size mechanism of hot rolled bearing steel with rare earth addition

Physical and physicochemical properties are considered for rare-earth elements (metals) and their reaction with oxygen, sulfur, and nonferrous metal admixtures during steel production. Introduction of REMs in optimum amounts makes it possible to modify nonmetallic inclusions both in a liquid condition and during steel crystallization, to refine cast workpiece structure due to inoculation action, and to improve physicomechanical and operating properties of a broad range of steels and alloys. Melt stirring is necessary in order to improve steel purity with respect to nonmetallic inclusions during REM introduction and subsequent steel treatment.

Modification of Steel and Alloys with Rare-Earth Elements. Part 1

The effect of technology of introducing REM on the composition and shape of nonmetallic inclusions and physicomechanical properties of carbon and low-alloy steels for different purposes is analyzed, and criteria are provided for REM consumption in relation to sulfur and oxygen content within metal, making it possible to determine the optimum REM distribution with which there is an increase in ductility properties, impact energy, and sheet and plate anisotropy properties of the sheet are reduced. Microalloying of carbon and alloy steels and alloys with REM improves corrosion resistance, hot ductility, thermal shock resistance, and other operating properties.

Modification of Steel and Alloys with Rare-Earth Elements. Part 2*

The content of nonmetallic inclusions when rail and wheel steel is produced by intensive modern technology and modified by rare-earth metals is analyzed. The composition, morphology, dimensions, and distribution of the inclusions in the steel are determined in the case without oxidation by aluminum or treatment by silicocalcium and also with treatment of aluminum-bearing steel by both rare-earth metals and silicocalcium. Modification with rare-earth metals reduces the content of oxide inclusions in the rail and wheel steel. That improves the plasticity and impact strength of the products.

Influence of rare-earth modification on the formation of nonmetallic inclusions in high-carbon steel

In the blast-furnace shop at OAO Nizhnetagil’skii Metallurgicheskii Kombinat (NTMK), the smelting of low-silica vanadium hot metal is being introduced. Theoretical and experimental data reveal the influence of the pressure in the furnace’s working space and coke quality on the reduction of titanium and the formation of refractory titanium compounds. The residence time of the melt in the hearth depends on its dimensions.

Smelting low-silica hot metal at OAO NTMK

Fusibility curves of FeO–La2O3–Al2O3, FeO–Ce2O3–Al2O3, La2O3– Ce2O3–Al2O3 oxide systems are created based on the literature data and modern thermodynamic theories of oxide and metal melts. Admitting the oxide systems conjugation with the area of metal melts existence, we define oxide phases, which can maintain the equilibrium with metal melts of Fe–Ce–Al–O, Fe–La–Ce–Al–O systems. The surfaces of component solubility are created for above mentioned metal melts. For Fe–Ce–Al–O system it is established that the following phases can be at equilibrium with metal: Al2O3, Сe2O3, FeO∙Al2O3, Сe2O3∙11Al2O3, Сe2O3∙Al2O3, and the oxide melt (FeO, Al2O3, Сe2O3, СeO2). For Fe–La–Ce–Al–O system the following oxide phases can be at equilibrium with the liquid metal: La2O3, Al2O3, Сe2O3, La2O3∙Al2O3, Сe2O3∙11Al2O3, Сe2O3∙Al2O3, and the oxide melt (FeO, La2O3, Al2O3, Сe2O3, СeO2). Diagrams of active components consumption, which are used to establish the possibility of chosen equilibrium, are created for iron deoxidation with cerium and aluminium as well as with Ce and La at fixed Al content (0.01 wt. %).

Smirnov Leonid A

Papers

Modification of Steel and Alloys with Rare-Earth Elements. Part 1

Modification of Steel and Alloys with Rare-Earth Elements. Part 2*

Influence of rare-earth modification on the formation of nonmetallic inclusions in high-carbon steel

Smelting low-silica hot metal at OAO NTMK

Thermodynamic Modelling of Rare-Earth Elements - Oxygen Interaction