Economic net-shape forming of TiAl alloys for automotive parts

Induction melting of γ-TiAl in CaO crucibles

“…Due to such a strict relationship, the microhardness depends significantly on the superheating temperature and cooling rate, because as those parameters increase and decrease respectively, the more extensive is the crucible material dissolution, with a consequent increase in the alloy oxygen content. Although the microhardness increases at the surface, the maximum value -326 HV -is significantly lower than those reported by other researchers for as cast Ti-48Al [10,14] and agree with the suggested microhardness values for this kind of alloy [19]. 6.…”

“…A possible way to reduce production costs might be the use of the ceramic crucible induction melting process, using suitable and low cost ceramic materials for crucible production, combined with the use of traditional melting stocks, avoiding expensive master alloys [9][10][11]. However this would only be possible in those cases where high melting point constituents like Nb or W, for example, are not used in the melting stock or their concentration in the cast alloy is low enough to avoid prolonged heating at high temperature, and consequent excessive oxygen pickup from the crucible wall.…”

“…Until now, no material was found to be absolutely inert against titanium alloys and during melting some interaction between the alloy and the crucible materials always occurs, leading to metal contamination [10][11][12]. Taking into account the free Gibbs energy of formation, CaO presents the most negative value among all metallic oxides if Y 2 O 3 is excluded, suggesting that it could be a good option to produce melting crucibles for titanium alloys.…”

Effects of the Al content on pore structures of porous Ti–Al alloys

“…This is due to their outstanding engineering performances such as excellent acid/alkali corrosion resistance and good oxidation resistance at elevated temperatures [4e6]. However, their intrinsic low tensile ductility at room temperature and poor high temperature strength have limited their potential applications, particularly in the aerospace field [7], although the TieAl alloy system has been used in the automotive industry in a limited scale [8,9].…”

On the Modification of Hydration Resistance of CaO with ZrO2 Additive

“…Induction melting is more energy efficient and preferred in preparation of titanium alloys when compared with the vacuum arc melting and cold heart melting as no forced water cooling system is needed. However, the crucible material for induction melting the titanium alloys needs to be carefully chosen because the titanium melts has high chemical activity, and can easily react with the crucible material to contaminate the titanium melts …”