Hypoeutectic Al-Si Alloy Doped with Chromium, Tungsten and Molybdenum Designated for Pressure Die Casting

Abstract

Structural modification of hypoeutectic Al-Si alloy EN-AC 46000 alloy influences its microstructure and mechanical properties. In a series of examinations the EN-AC 46000 alloy has been doped with Cr, W and Mo. The study involved the differential thermal analysis (DTA) and the light microscopy structural analysis of the samples cut from pressure die castings and from samples cast into the DTA cup. The DTA and microstructure analyses revealed new phases in the alloy doped with mentioned additives. The strength properties measurements of the alloys doped with Cr, W and Mo showed significant improvement in tensile strength and elongation, while preserving good hardness.

Microstructural Characteristics of AlSi9Cu3(Fe) Alloy with High Melting Point Elements

“…They were manufactured on a cold-chamber die casting machine Idra 700S (IDRA, Travagliato, Italy). The shell mold, on the other hand, was made of a shell sand, it had the form of a probe, the dimensions of which are presented in [3]. A thermal and derivative analysis of the crystallization process of the tested alloys was carried out with the use of a above mentioned probe equipped with a PtRh10-Pt thermocouple.…”

“…The derivative curve shows three thermal effects: C s AB, BEH, and HKL. According to the data presented in [3], these are the effects caused by the crystallization of α(Al) solid solution, ternary eutectic α(Al) + Al 15 (Fe,Mn) 3 Si 2 + β(Si) and quaternary eutectic α(Al) + Al 2 Cu + AlSiCuFeMgMnNi + β(Si). The authors of [40][41][42] show that in the case of multicomponent hypoeutectic al-Si alloys, after the crystallization of the primary α(Al) phase, complex eutectic mixtures usually crystallize, in which the α(Al) and β(Si) solid solutions and intermetallic phases appear as component phases.…”

“…Then, as a result of the peritectic transformation, the lamellar intermetallic phase β-Al 5 FeSi is formed, and afterwards three eutectic mixtures crystallize successively: α(Al) + β(Si) eutectic mixture and two complex mixtures containing Mg 2 Si and Al 2 Cu phases. On the other hand, in [3], the authors present the three-stage process of EN AC-46000 alloy crystallization based on the derivative and thermal analysis. According to the presented data, the crystallization process starts with the crystallization of α(Al) dendrites, then two complex eutectic mixtures crystallize: ternary and quaternary.…”

“…The β-Al 5 FeSi phase crystallizes in the alloy with a relatively low manganese and chromium content. At 0.15 wt % Mn or more, Al 15 (Fe,Mn) 3 Si 2 phase appears in the microstructure. If 0.15 wt % chromium is present in the alloy, its atoms are attached to this phase.…”

Archives of Foundry Engineering

“…Al-Si casting alloys are characterized by soft matrix and hard precipitations of silicon. Except silicon, these alloys can consist of small additions of other elements having effect on mechanical properties of the alloys by change of structure and course of crystallization process [1][2][3][4][5][6][7]. Mechanical and technological features of aluminum-silicon alloys, originated mainly from size, shape and distribution of precipitations of primary silicon crystals (hyper-eutectoid alloys) and eutectic ones (hypo-eutectoid and eutectoid alloys) directly affect application field of these alloys [1,4,6,[8][9][10].…”