Papers by Keyword: Mischmetal

Abstract: The thermal conductivities of quaternary Mg-Zn-Ca-MM alloys have been investigated by evaluating the effect of MM on Mg-4Zn-0.5Ca alloys, with an emphasis to develop a new Mg alloy without compromising thermal conductivity, process-ability and mechanical property. As a result, the thermal conductivity of 0.5 wt.% MM-added Mg-Zn-Ca alloy was almost same as that of MM-free Mg-Zn-Ca alloy. However, with further increasing MM contents, thermal conductivities of MM-added alloys decreased. The tensile yield strength was improved with increasing MM contents. In addition, the average spiral flow lengths of Mg-Zn-Ca-xMM alloys were almost same levels with Mg-Zn-Ca alloy.

Abstract: Solution treatments (T4) at 380 °C for 16 h and 500 °C for 8 h were performed for ZK60 magnesium alloys modified with addition of 0.5, 1.5 and 2.5 wt% of mischmetal (combination of rare-earth (RE) elements). The compression behaviour was investigated at room temperature and at 300 °C correlated with the microstructure and differential scanning calorimetry (DSC) data. The as-cast microstructure is formed by a-Mg matrix with globular grains reinforced by a semi continuous network of Mg-Zn, Mg-Zn-RE and Mg-RE intermetallic particles. Solution-treated alloys show lower yield strengths due to partial dissolution of precipitates. Work hardening was not observed for the alloys compressed at 300°C with the compression speed of 10^-3 s^-1, whereas it was observed for the compression speed of 10^-2 s^-1 for the all as-cast, ZK60-1.5RE-T4 at 380 °C and ZK60-1.5RE-T4 at 380 °C.

Abstract: Effect of antimony on the microstructure, especially on the morphologies of rare earth-enriched phases, of mischmetal -containing AZ31 alloy was studied. The results showed that, by the addition of 0.8%Sb, the rare earth-enriched phases in AZ31-1.0％MM were transformed to dispersive tiny sphere-like Al-rare earth-Sb phases from coarse needle-like Al-rare earth phases. Meanwhile, rare earth-enriched phases transferred into α-Mg crystal grains from grain boundaries. On the other hand, the distribution of β-Mg17Al12 phases became more dispersive.

Abstract: Mechanical milling (MM) and a combination of MM and temperature heating were used to synthesize the intermetallic MmNi5 and a MmNi5-Ni mixture, respectively. The process evolution with time was analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM was used to characterize size and morphology of particles in order to reveal the governing mechanisms during the milling of each system. X-ray diffraction (XRD) was utilized to determine strain and crystallite size changes introduced by milling. The effects of integrated milling time on the sorption properties of the MmNi5-Ni mixture were analyzed. Results were correlated to defects introduced into microstructure. A comparison of the final characteristics of alloys obtained in each case is also shown.

Abstract: In this work, the effect of mischmetal (48wt%Ce–27wt%La–14wt%Nd–6wt%Pr) additions on the microstructural characteristics of an Cu-7wt%P brazing filler metal (BCuP-2) were investigated. The volume fraction of primary Cu was considerably increased with increasing mischmetal addition in the BCuP-2. Also, the eutectic structure was changed from lamella to fibrous morphology and the pseudo-eutectic phase (Cu3P) was formed around the primary Cu with the mischmetal addition above 0.03wt%. Compound containing a small amount of mischmetal was formed in the primary Cu phase and this compound acts as the nucleation sites of primary Cu. The fraction of primary Cu was increased by about 1-2wt% due to the mischmetal rich phase. The mischmetal rich phase also formed in the pseudo-eutectic phase and this enhanced the formation of pseudo-eutectic phase. The addition of mischmetal changes the eutectic phase lamella to fibrous by suppressing both the solid-liquid interfacial energy and the surface energy of the solid. The mischmetal additions showed a very strong influence on the nucleation process of primary Cu and the subsequent formation of Cu3P phase as well as the eutectic structure change.