Cubic and hexagonal a-phases, formed during thermal analysis experiments and specific isothermal treatments, have been analyzed for a series of Al-Mn-Si alloys with different iron contents. In these alloys, the Fe/Mn weight ratio was varied from 0.1 to 8.4. This study shows that in Al-Fe-Mn-Si alloys with Fe/Mn weight ratios up to 4, the a-phase has a cubic crystal structure, while in alloys with a Fe/Mn weight ratio of 5.3 or more, the a-phase has a hexagonal crystal structure. Hence, the critical Fe/Mn weight ratio for the cubic to hexagonal crystal structure transition falls between 4 and 5.3 for the studied alloys. KeywordsAluminum alloys; Intermetallic Al-Fe-Mn-Si phases; X-ray analysis diffraction; Crystal structure type.Efecto de la adición de hierro sobre la estructura cristalina de la fase a-AlFeMnSi formada en el sistema cuaternario Al-Fe-Mn-Si ResumenLas fases a de estructura cristalina cúbica y hexagonal, formadas durante los ensayos de análisis térmico y tratamientos isotérmicos específicos, han sido analizadas para una serie de aleaciones Al-Mn-Si con diferente contenido de hierro. En estas aleaciones, la relación en peso Fe/Mn se varió de 0,1 a 8,4. Este estudio muestra que las aleaciones Al-13,4Si-1,1 Mn-Fe con relación en peso Fe/Mn menor o igual a 4, la fase a presenta estructura cristalina cúbica, mientras que en aleaciones con una relación Fe/Mn igual o mayor a 5,3, la fase a presenta estructura cristalina hexagonal. Por lo tanto, la relación crítica Fe/Mn para la transición de estructura cristalina de cúbica a hexagonal se encuentra entre 4 y 5,3 para las aleaciones estudiadas. Palabras claveAleaciones de aluminio; Compuestos intermetálicos Al-Fe-Mn-Si; Difracción de rayos X; Tipo de estructura cristalina.P. OROZCO-gONZálEZ, M. CASTRO-ROMáN, J. lóPEZ-CUEVAS, A. HERNáNDEZ-RODRígUEZ, R. MUñIZ-VAlDEZ, S. lUNA-álVAREZ AND C. ORTIZ-CUEllAR 454 Rev. metal. 47 (6), NOVIEMBRE-DICIEMBRE, 453-461, 2011, ISSN: 0034-8570, eISSN: 1988-4222, doi: 10.3989/revmetalm.1068 1.2, the presence of cubic a and a bcc -AlFeMnSi phases, the latter described as Al 19 Fe 4 MnSi 2 , has been reported [5] . The formation of a hexagonal a h -AlFeMnSi phase, with a formula of Al 8 Fe 2 Si, has also been reported [6, 10 and 11] . Tibballs et al. [12] studied a set of eight alloys of the Al-(6-8)Si-(0.4-3.5)Fe-(0.1-3.6)Mn system. They reported the precipitation of a cubic a c -AlFeMnSi phase in alloys with a Fe/Mn weight ratio up to 8.3, whereas the a h -AlFeMnSi was the stable phase in alloys with a Fe/Mn ratio equal or higher than 12.5.From the point of view of the improvement of the available thermodynamic databases, the study of Al-Fe-Mn-Si system and other alloy systems is gaining importance in basic and applied research. Ravi and Wolverton [13] made a critical comparison of the two commercially available Al-alloy thermodynamic databases: Thermotech and Computherm. They observed some differences in the databases with regard to the intermetallic compounds involving iron, manganese, chromium, and zinc. Thus, they...

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Iron-chromium cast alloys are basically abrasive wear resistant materials particularly employed in mining industry; these alloys are often utilized in the manufacture of milling balls. In particular, high Cr and high C cast alloys have been subjected of significant research; for instance, most reports have been addressed on analyzing the relation between microstructure and the abrasive wear behavior; however, there exist a reduced number of reports on relatively low Cr and low C cast alloys. In this research, five low Cr cast steels containing additions of V and Ti were melted in an open atmosphere induction furnace. Comparisons on the morphology, size, type and distribution of carbides were carried through optical microscopy, SEM and XRD. Hardness testing was employed at room temperature with the purpose of correlate to wear behavior. A laboratory pilotplant ball-mill set with a batch of ore was utilized in order to evaluate the abrasive wear resistance. According to microstructure observations, a martensitic primary matrix was revealed in all specimens. The fraction of M7C3 and M 3 C interdendritic eutectic carbides varied according to alloying level. Further results indicated that variations in the shape and size of M 7 C 3 and M 3 C along with the presence of V and Ti carbides influenced on the abrasive wear behavior of low Cr cast steel mill balls.

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