1. History of Bulk Amorphous Alloys 2. High Glass-Forming Ability and its Dominant Factors 3. Compositional Dependence of the Dominant Factors for GlassFormation, Tx and Tg/Tm. 3.1. Ln-Al-(Ni,Cu) Systems 3.2. Mg-Ln-(Ni,Cu) Systems 3.3. Zr-Al-TM Systems 3.4. Pd-Cu-Ni-P System 4. Continuous Cooling Transformation Behavior of SupercooledLiquid and Critical Cooling Rate for Glass Formation 5. Preparation Methods of Bulk Amorphous Alloys. 5.1. High-Pressure Die Casting Method. 5.2. Water Quenching Method 5.3. Copper Mold Casting Method 5.4. Arc Melting Method 5.5. Unidirectional Zone Melting Method 5.6. Suction Casting Method 6. Compositional Dependence of Maximum Sample Thickness (tmax). 6.1. La-Al-(Co,Ni,Cu) Systems 6.2. Zr-Al-(Co,Ni,Cu) Systems 6.3. Zr-Al-Ni-Cu-TM (TM = Transition Metals) Systems 7. Structure of Bulk Amorphous Alloys. 7.1. Mg-La-Ni System 7.2. La-Al-Ni System 7.3. Zr-Al-Ni System 7.4. Zr-Y-Al-Ni System 8. Structural Relaxation and Thermal Stability. 8.1. Structural Relaxation 8.2. Glass Transition 8.3. Two-Stage Glass Transition 8.4. Crystallization Behavior 9. Physical Properties. 9.1. Density 9.2. Specific Heat 9.3. Viscosity 9.4. Atomic Diffusivity 9.5. Electrical Resistivity 9.6. Thermal Expansion

Bulk Amorphous Alloys : preparation and Fundamental Characteristics

Attempts have been made to prepare highly dense bulk Al-based nanocomposite consisting of evenly distributed nano-intermetallic particles and amorphous phase by consolidating mechanically alloyed amorphous Al88Ni6Ti6 powder using spark plasma sintering (SPS), hot-pressing and pressure-less sintering techniques. SPS technique has been most effective in comparison to other two processes in getting better homogeneity of microstructural features, densification and mechanical properties due to lower sintering temperature and time, hindering excessive crystallization of amorphous phase and grain growth of formed nanocrystals. This helps in producing optimum microstructure consisting of homogeneous distribution of nanocrystalline intermetallic phase and remaining amorphous phase as revealed by detailed electron microscopy and nano-indentation tests.

Structure and mechanical properties of Al–Ni–Ti amorphous powder consolidated by pressure-less, pressure-assisted and spark plasma sintering

https://www.skpabi.com/documents/skp%20publications/95%29%20Powder%20Tech.,%20191%20%282009%29%20176-181.pdf

On the formation of phases by mechanical alloying and their thermal stability in Al-Mn-Ce system

Ball milling with high energy for mechanical alloying was followed to make Ni-Fe alloy powders from elemental Ni and Fe powders having the sizes of 80 µm (Ni) and 25 µm (Fe). Preparations were carried out at room temperature with various duration of time ranging from 2 to 100 hours using ball milling with high energy. Analyses based on X-ray diffraction pattern and particle size analyzer were used for characterization of powders. During ball milling, it was observed that the reduction of grain size and particle size occurred in a stepped fashion. This observation indicates that the reduction in grain size and particle size occurs in a successive cyclic fashion, contrary to the expectation of concurrent reduction.

Mechanism of Reduction in Grain and Particle Sizes of Nix-Fe100x Nanopowder by Mechanical Alloying

Vacuum brazing of TiAl-based alloy and GH536 superalloy with a low-melting point amorphous Ti35Zr25Be30Co10 filler

Amorphous structure generated by mechanical alloying (MA) is often used as a precursor for generating nanocomposites through controlled devitrification. The amorphous forming composition range of ternary Al-Ni-Ti system was calculated using the extended Miedema’s semi-empirical model. Eleven compositions of this system showing a wide range of negative enthalpy of mixing (−ΔHmix) and amorphization (−ΔHamor) of the constituent elements were selected for synthesis by MA. The Al88Ni6Ti6 alloy with relatively small negative ΔHmix (−0.4 kJ/mol) and ΔHamor (−14.8 kJ/mol) became completely amorphous after 120 h of milling, which is possibly the first report of complete amorphization of an Al-based rare earth element free Al-TM-TM system (TM = transition metal) by MA. The alloys of other compositions selected had much more negative ΔHmix and Hamor; but they yielded either nanocomposites of partial amorphous and crystalline structure or no amorphous phase at all in the as-milled condition, evidencing a high degree of stability of the intermetallic phases under the MA environment. Hence, the negative ΔHmix and ΔHamor are not so reliable for predicting the amorphization in the present system by MA

B. S. Murty

Papers

On amorphization and nanocomposite formation in Al-Ni-Ti system by mechanical alloying