The Al-Mo system (aluminum-molybdenum)

Abstract

The AI-Mo system is of a complex type, and a variety of phases are reported as being stable [Hansen, Elliott, Schunk].[80Bre] reviewed the literature and gave a phase diagram. The diagram presented here (Fig. 1, Table 1) differs in a number of aspects from [80Bre] and is based on a review of original data and thermodynamic calculations. AI-Rich Alloys (0 to 33 at.% Mo) The composition of the Al-rich liquidus is well established up to 1000 ~ [40Yam, 76Yer, 80Mal] (Fig. 2, Table 2). Based on this and the solid solubility measurements of Mo in A1 reported by [43Mon] and [60Vig] (Table 2), the most Al-rich reaction is a peritectic between the AI solid solution and All2Mo. This differs from [80Bre], who assumed a eutectic reaction.There is uncertainty concerning the stability of, and the exact sequence of, reactions involving the Al-rich intermetallic compounds.[64Wall] reviewed the available data previous to 1964 and put forward the reaction sequence shown in Fig. 3, where four peritectic reactions are postulated at 1130, 800, 735, and 700 ~ This review formed the basis for the reaction sequence given by [80Bre]. There is experimental evidence for reactions at ~ 1130 ~ [22Rei, 59Spe], -735 ~ [22Rei, 52Wac, 59Spe], and -700 ~ [40Yarn, 59Spe, 60Cla]. The peritectic reactions reported by [72Kam] at 717 and 684 ~ correspond to those at 735 and 700 ~ but lie -17 ~ lower.A review of the literature shows that the peritectic at 700 ~ is associated with the formation of All2MO [59Spe, 60Cla, 72Kam] and the peritectic at 735 ~ with

Physical properties of noncentrosymmetric tungsten and molybdenum aluminides

“…Alumina lids were used on all Al-Mo growths. The Al-Mo phase diagram is significantly more complicated than that of Al-W, with a cascade of noncentrosymmet-ric phases around the composition range between Al 4 Mo and Al 5 Mo [16][17][18][19][20][21] . Most of the recent phase diagrams indicate an Al 4 Mo phase that melts peritectically around 1150 • C and decomposes around 950 • C, Al 17 Mo 4 which melts peritectically around 1000 • C, Al 22 Mo 5 with a peritectic decomposition at 950 • C but possibly only stable above 830 • C, then around 850 • C Al 5 Mo begins to form.…”

Phase equilibria in the Al–Mo–Si system

“…The Al-Mo binary system was assessed by Saunders [11] and contains, according to this author, 7 intermetallic phases: AlMo 3 (Pm-3n, cP8, CrSi-type), AlMo (Im-3m, cI2, W-type), Al 63 Mo 37 (unknown structure), Al 8 Mo 3 (C2/m, mC22, Al 8 Mo 3 -type), Al 4 Mo (Cm, mC30, Al 4 W-type), Al 5 Mo (P6 3 , hP12, Al 5 W-type), and Al 12 Mo (Im-3, cI26, Al 12 W-type). AlMo and Al 63 Mo 37 are stable only at elevated temperatures and were reported by Rexer [12].…”

“…The temperatures of the invariant reactions were slightly corrected (see Table 1) and the phase Al 22 Mo 4 was found to exist at 600 C as well, although this was not confirmed by diffusion couple experiments at 630 C [15]. Okamoto [16] presents a phase diagram combining the results of Rexer [12], Saunders [11] and Eumann [15]. The binary AleSi system is a simple eutectic system with limited solid solubility in Al and Si [17].…”

Laser surface alloying of molybdenum on aluminum for enhanced wear resistance

“…In Al-Mo phase diagram [22] there are nine intermetallics which exist at various temperatures and compositions. In this regard, it is relevant to mention that the formation of these intermetallics during LSA is mainly dependent on two conditions 1) chemical composition which is mainly dependent on dilution of Mo in Al and 2) thermodynamic conditions such as cooling rates, enthalpy of formation (ΔH f ), and Gibbs free energy ( …”