Glass-forming ability, thermal stability, mechanical and electrochemical behavior of Al-Ce-TM (TM = Ti, Cr, Mn, Fe, Co, Ni and Cu) amorphous alloys

Abstract Al 86 Ce 10 TM 4 amorphous alloys (TM = Ti, Cr, Mn, Fe, Co, Ni and Cu; where the alloys are denoted by A 1 ~A 7 , respectively) were fabricated using melt-spin fast-quenching method. The glass-forming ability (GFA), thermal stability (TS), and mechanical and corrosion behavior of the as-spun alloys were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy - energy dispersive spectroscopy (SEM-EDS), differential scanning calorimetry (DSC), micro-indentation and electrochemical techniques. It was found Al and Ce microalloyed with Ti, Cr, Mn, Fe, Co, Ni and Cu, respectively enhance glass formation, thus the as-spun Al 86 Ce 10 TM 4 alloys form an amorphous matrix embedded with short range ordered (SRO) Al-TM, Al-Ce and Al-Ce-TM quasi-crystalline clusters due to a strong heteroatomic interaction related to a covalent character of atomic bonds (for A 1 ~A 7 ) or/and inlaid with face-centered-cubic aluminum (FCC-Al) nano-crystallites which were precipitated during the melt-spin quenching (for A 1 ~A 3 ). The GFA of the alloys ranks in the sequence of A 4  >  A 5  >  A 6  >  A 7  >  A 2  >  A 3  >  A 1 which can be assessed by the supercooled liquid region ΔT m (= T m - T x ) , the reduced glass transition temperature T rg (= T g / T m ), and other criteria such as γ′  =  T x /( T g + T m ), δ′  =  T x /( T m  −  T g ), β′  =  T x T g /( T m + T x ) 2 , and ω′  =  T m ( T m + T x )/( T x ( T m  −  T x )); while the TS of the alloys lists in the series of A 5  >  A 6 ~ A 4  >  A 7  >  A 3  >  A 2  >  A 1 that can be evaluated by the first crystallization activation energy E c , first crystallization activation enthalpy ΔH ⁎ , frequency factor K o , fragility parameter m , and theoretical glass transition temperature T g ⁎ . The hardness of the alloys A 1 ~A 7 accounts to 707, 809, 940, 863, 762, 809, and 715 MPa, respectively, attributing to a composite structure consisting of an amorphous matrix tessellated with SRO quasi-crystalline clusters or/and FCC-Al nano-crystallites. In addition, the alloys exhibit high corrosion resistance in the rate of 10 −7 –10 −8 A/cm 2 with a large passivation scope except that the alloy A 7 presents a corrosion rate of 10 −6 A/cm 2 with an active anodic dissolution behavior. The results manifest the Al 86 Ce 10 TM 4 alloys can be fabricated into a unique composite consisting of an amorphous matrix embedded with SRO quasi-crystalline or/and nano-crystalline phases which confers high mechanical hardness and corrosion resistance for potential engineering applications.