Functional and Environmental Advantage of Cleaning Ti5B1 Master Alloy

Abstract

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 TiAl 3 and TiB 2 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.

A Review on the Analysis of Thermal and Thermodynamic Aspects of Grain Refinement of Aluminum-Silicon-Based Alloys

“…If the concentrations are high enough, there is first the formation of TiB 2 particles. Moreover, if the stoichiometric ratio is high, there is a surplus of Ti and the solidification of the alloy is accompanied by the monotectic and peritectic reactions associated with titanium [ 11 , 12 , 14 , 15 , 16 , 17 , 18 ]. Conversely, if the Ti:B ratio is low (titanium deficiency), there is formation of a metastable phase (Al,Ti)B 2 [ 10 , 19 , 20 , 21 ].…”

“…Using cleaner Ti-5B master alloy with a higher number of TiAl 3 and TiB 2 particles improves its grain refinement efficiency and transmits fewer impurities in produced parts. Producing a cleaner master alloy would be beneficial from economic and environmental aspects by increasing its value and the service time of the produced parts, as well as simplifying the recycling process at the end of the life-cycle of these parts [ 11 ].…”