Grain refinement efficiency of a new oxide-containing master alloy for aluminium casting alloys

In this study, grain refinement efficiency of a new oxide master alloy based on MgAl2O4 was demonstrated on an A357 alloy. The grain size of the reference alloy was reduced by 50-60% with the addition of the master alloy and introduction of ultrasonic cavitation. A higher addition of master alloy was found to be not benificial in further reducing the grain size.The ExoMet Project, which is co-funded by the European Commission in the 7th Framework Programme (contract FP7-NMP3-LA-2012-280421), by the European Space Agency and by the individual partner organisations

Effect of Al addition on microstructure of AZ91D

Casting is a net shape or near net shape forming process so work-hardening will not be applicable for improving properties of magnesium cast alloys. Grain refinement, solid-solution strengthening, precipitation hardening and specially designed heat treatment are the techniques used to enhance the properties of these alloys. This research focusses on grain refinement of magnesium alloy AZ91D, which is a widely used commercial cast alloy. Recently, Al-B based master alloys have shown potential in grain refining AZ91D. A comparative study of the grain refinement of AZ91D by addition of 0.02wt%B, 0.04wt%B, 0.1wt%B, 0.5wt%B and 1.0wt%B of A1-5B master alloy and equivalent amount of solute element aluminium is described in this paper. Hardness profile of AZ91D alloyed with boron and aluminium is compared

Research on the Process of Al–Mo–Ti Master Alloy Dissolution in Titanium

This paper presents the results of studying the behavior of the components of the molybdenum-containing Al-(48-52)Mo-(6-9)Ti (wt. %) master alloy when it is dissolved in liquid titanium. The nature and characteristics of the dissolution of the master alloy in titanium were judged by the results of X-ray microanalysis of the matrix phases (titanium, master alloy) and transition zones (phase boundary). In order to bring the model closer to actual melting conditions, a vacuum arc melting of a titanium sample was used, in which a certain amount of master alloy was encapsulated. The samples were melted around the perimeter so that the liquid titanium only began to interact with the master alloy, after which the melting process was stopped. The obtained results suggest that the composition of the Al-Mo-Ti master alloy is changed by the diffusion transition of molybdenum and aluminum into the titanium melt and counter diffusion of titanium into the master alloy melt. At the same time, a decrease in the concentration of molybdenum in the master alloy is compensated by aluminum and titanium. For every 1.0 wt. % of Al converted into Ti about 2.0 wt. % of Ti dissolves in the master alloy melt. The revealed patterns of changes in the composition of the Al-Mo-Ti master alloy when interacting with liquid titanium suggest that under vacuum-arc melting of titanium alloys the dissolution of the master alloy should not lead to the formation of refractory phases. Keywords: titanium, molybdenum, aluminum, master alloys, dissolutio

A new Al-Zr-Ti master alloy for ultrasonic grain refinement of wrought and foundry aluminum alloys

A new grain refiner master alloy based on the Al-Zr-Ti system was prepared by salt assisted synthesis. 90% of Al3Zr particles in the master alloy were ranged between 1 and 13 μm. 80% reduction of grain size was observed with the addition of 0.2wt% Zr equivalent master alloy combined with ultrasonic treatment in an Al alloy. The new master alloy demonstrated 30% improvement in grain refinement efficiency compared to the one prepared by a conventional alloy route.The authors wish to acknowledge financial support from the ExoMet Project, which is co-funded by the European Commission in the 7th Framework Programme (contract FP7-NMP3-LA-2012-280421), by the European Space Agency and by the individual partner organisations

Functional and Environmental Advantage of Cleaning Ti5B1 Master Alloy

One of the greatest environmental goals for the aluminum alloys industry is generating higher quality products by introducing cleaner input materials while maintaining low production costs. A typical dilemma for the master alloy producers is the cleanness level of the master alloy since insoluble inclusions could serve as inoculants during the solidification process. In this work, commercial Ti5B1 master alloy is used for grain refinement of Al7Si4Cu aluminum alloy and compared with the cleaned master alloy that contained a lower amount of residual refractory oxides and salts. Metallography analysis was used for grain size measurement while Computer Aided Cooling Curve Analysis was used for assessment of the undercooling and heat release values. In all instances, specimens treated with the cleaned master alloy showed smaller grains in the final structure and lower undercooling values. The difference in released heat between liquidus and recalescence temperatures was about 25% in specimens where added 0.66 wt% of cleaned master alloys compared to specimens where the commercial master alloys were added. Using cleaner Ti5B1 master alloy with a higher number of TiAl3 and TiB2 particles improves its grain refinement efficiency and transmits fewer impurities in produced parts. Producing cleaner master alloy would be beneficial from economic and environmental aspects by increasing its value and service time of produced parts besides simplifying the recycling process at the end of parts life-cycle.This is the peer reviewed version of the paper: Mitrašinović, A., Tomić, M., 2021. Functional and Environmental Advantage of Cleaning Ti5B1 Master Alloy, International Journal of Precision Engineering and Manufacturing-Green Technology, [https://doi.org/10.1007/s40684-021-00339-2

Application Of Ni-Mg-Ce Master Alloy Scrap For Inoculation Of Copper-Nickel Alloys

The problems of production of copper-nicckel alloys ingots by semicontinuous casting method are analysed. The requirement of grain size refinement in cast alloys macrostructure is shown. It is necessary to reduce the probability of hot cracks formation and increase the fabricability of cast bars during plastic working. The reasonability of fine fraction of Ni-Mg-Ce master alloy application for inoculation of copper-nickel alloys is established. The results of laboratory experiments on the study of master alloy quantity influence the structure and hardness of Cu-5Ni-1Fe, Cu-10Ni-1Fe-1Mn and Cu-30Ni-1Fe-1Mn copper-nickel alloys are presented. On the basis of industrial experiments it is revealed that inoculation of Cu-5Ni-Fe alloy ingots of diameter 200 mm by Ni-Mg-Ce master alloy leads to considerable reducing of macrograin size. It allows to improve mechanical properties of ingots and ensure their uniform distribution in cross section of ingots. It is established that  residual magnesium content in alloy must be in range from 0,02 to 0,06 wt. %. The use of  Ni-Mg-Ce master alloy makes it possible to increase the processability of copper-nickel alloys during plastic working and utilize the fine fraction master alloy scrap inevitably formed during its production. Keywords: Copper-nickel alloys, Semicontinuos casting, Ingot, Inoculation, Ni-Mg-Ce master alloy, Structure, Mechanical propertie

Development Of Al-B-C Master Alloy Under External Fields

This study investigates the application of external fields in the development of an Al-B-C alloy, with the aim of synthesizing in situ Al3BC particles. A combination of ultrasonic cavitation and distributive mixing was applied for uniform dispersion of insoluble graphite particles in the Al melt, improving their wettability and its subsequent incorporation into the Al matrix. Lower operating temperatures facilitated the reduction in the amount of large clusters of reaction phases, with Al3BC being identified as the main phase in XRD analysis. The distribution of Al3BC particles was quantitatively evaluated. Grain refinement experiments reveal that Al-B-C alloy can act as a master alloy for Al-4Cu and AZ91D alloys, with average grain size reduction around 50% each at 1wt%Al-1.5B-2C additions

Optimization of casting process parameters for synthesis of Al-Nb-B master alloy

Al-Nb-B master alloys were synthesized using commercial pure aluminum, niobium, and KBF4 salts. Two different sources of Nb (pure Nb powder and Al-60%Nb powder) were used to prepare the master alloy. Casting process parameters such as reaction time and melt stir time interval were varied to enhance the formation of in situ intermetallic particles in the master alloys. The size, shape and distribution of intermetallic particles in these master alloys were studied using microscopy techniques. The results show that the Al-5Nb-1B master alloy prepared with Al-60%Nb powders has a uniform distribution of intermetallic particles as compared to the master alloy prepared with pure Nb powders. Increase in boron content from 1 wt.% to 2 wt.% in the master alloys resulted in a higher fraction of intermetallic particles. Among all the master alloys synthesized, Al-5Nb-2B was observed to have the highest number of well-distributed intermetallic particles which could act as potential grain refiners of aluminum alloys

Effects of spherical quasi-crystal on microstructure and mechanical properties of ZA155 high zinc magnesium alloy

Effects of spherical quasi-crystal contained in Mg-Zn-Y-Mn master alloy on the microstructure and as-cast mechanical properties of ZA155 high zinc magnesium alloy have been investigated by means of optical microscopy, XRD, SEM, EDS, tensile test, impact test and hardness test. Experimental results show that the addition of spherical quasi-crystal contained in the Mg-Zn-Y-Mn master alloy into the ZA155 high zinc magnesium alloy resulted in grain refinement of the matrix, changing the morphologies of φ-Al2Mg5Zn2 phase and τ-Mg32(Al, Zn)49 phase from continuous net-like structures to discontinuous strip-like structure and blocky one, respectively. In the present research, the best comprehensive mechanical properties of reinforced ZA155 high zinc magnesium alloy has been obtained when 5.0wt% spherical quasi-crystal was introduced from the Mg-Zn-Y-Mn master alloy into the target alloy system. In such case, the room-temperature tensile strength reached 207 MPa, about 23% higher than that of the base alloy; the impact toughness peaked at 5.5 J/cm2, about 40% higher than that of the base alloy; and the elevated-temperature tensile strength reached 203 MPa, indicating improved heat resistance

Damping Properties vs. Structure Fineness of the High-zinc Aluminum Alloys

The subject of this study is the presentation of relation between the degree of structure fineness and ultrasonic wave dampingcoefficient for the high-zinc aluminium alloys represented in this study by the sand mould cast alloy Al - 20 wt% Zn (AlZn20). Thestudied alloy was refined with a modifying (Al,Zn)-Ti3 ternary master alloy, introducing Ti in the amount of 400 pm into metal. Based on the analysis of the initial and modified alloy macrostructure images and ultrasonic testing, it was found that the addition of (Al,Zn)-Ti3 master alloy, alongside a significant fragmentation of grains, does not reduce the coefficient of ultrasonic waves with a frequency of 1 MHz