Preparation and Mechanical Properties of Zr-based Bulk Nanocrystalline Alloys Containing Compound and Amorphous Phases

High-strength Zr-based bulk amorphous alloys containing nanocrystalline and nanoquasicrystalline particles

“…In particular, the bulk amorphous alloy containing 20-30% of compound particles with a size of about 5 nm exhibits a high flexural strength of 4400 MPa which is about 2.2 times higher than that of the amorphous single phase alloy. Here, we focus on the recent results on the nanocrystalline [12,[14][15][16][17] and nanoquasicrystalline [13,[18][19][20][21][22] Zr-based bulk amorphous alloys after a brief description on the bulk amorphous single phase alloy. Fig.…”

“…The previous data [28] indicate the following criteria for the formation of a nanocrystalline structure: (1) multistage crystallization processes; (2) high nucleation frequency; (3) low growth rate; and (4) enhancement of the thermal stability of the remaining amorphous phase caused by the redistribution of a solute element at the nanocrystal/amorphous interface. With the aim of satisfying the criteria for the formation of a nanocrystalline structure, the influence of additional elements (M) on the crystallized structure was examined for the Zr-Al-Cu-M alloys [12,[14][15][16][17]. The additional (M) elements can be divided into three groups: (1) Pd, Pt and Au elements with much larger negative heats of mixing against Zr as compared with other atomic pairs; (2) Ti and Nb with nearly zero heat of mixing against Zr; and (3) Ag with a positive heat of mixing against Ni and Cu [29].…”

Microstructure and mechanical properties of slowly cooled Cu47.5Zr47.5Al5

“…6 To overcome the problem of limited plasticity in BMGs, several composite materials have been developed, [7][8][9][10][11][12][13][14][15][16][17] which can be broadly classified in two groups according to their processing: (i) ex situ and (ii) in situ formed composites. Several trials have previously been made to improve the ductility by introducing quasicrystalline 18,19 or nanocrystalline 20,21 precipitates in a glassy matrix upon partial crystallization during annealing treatment of the amorphous precursors. The ex situ composites are formed by directly introducing a crystalline solid phase as reinforcement into the glass-forming melt during processing and consist of either particle reinforcements [7][8][9] or fiber reinforcements 9,11 (continuous or discontinuous fibers).…”

Effects of Ti on the Thermal Stability and Glass-Forming Ability of Ni-Nb Glassy Alloy

“…11,13,14) It has previously been reported that a Ni 62.4 Nb 37.6 binary glassy alloy has a high reduced glass transition temperature of 0.61 and a rather low critical cooling rate of 1.4 × 10 3 K/s, 15) indicating that a high GFA may be obtained in more multi-component Ni-Nb based system. 13,14) Good mechanical properties are obtained for bulk glassy alloys in the Ln-, 16) Mg-, 5) Zr-, 17,18) and the Pd-Cu- 19) based systems, but the compressive fracture strength level of these glassy alloys is less than 2000 MPa. Recently, it has been reported that the Hf-, 20) Ni- 21) and a series of Cu-based [22][23][24][25][26] bulk glassy alloys exhibit high compressive fracture strength of 2000 to 2700 MPa.…”