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To circumvent the limited ductility of bulk metallic glasses (BMGs), heterogeneous materials with glassy matrix and different type and length-scale of heterogeneities (micrometer-sized second phase particles or fibers, nanocrystals in a glassy matrix, phase separated regions, variations in short-range order by clustering) have been developed in order to control the mechanical properties. As example, recent results obtained for Cu- and Ti-base structurally imhomogeneous bulk metallic glasses will be presented. This type of clustered glasses is able to achieve high strength together with pronounced work hardening and large ductility by controlling the instabilities otherwise responsible for early failure. We emphasize the possibilities to manipulate such spatially inhomogeneous glassy structures based on martensitic alloys in favor of either strength and ductility, or a combination of both and also discuss the acquired ability to synthesize such M-glasses in bulk form through inexpensive processing routes.

A series of Ti 44 Cu 44-x Co 4 Zr 6 Sn 2 Be x bulk metallic glasses with x = 0-5.1 has been systematically investigated in terms of glass-forming ability and mechanical properties at room temperature. With the small amount of Be addition, the glass forming ability as well as ductility can be significantly increased leading to the fully amorphous rod having the diameter larger than 4mm and ductility larger than 10%. Upon compressing the bulk metallic glass Ti 44 Cu 38.9 Co 4 Zr 6 Sn 2 Be 5.1 a work hardening-like behavior that may be attributed to structural heteorgeniety was observed.

We report ductile bulk metallic glasses based on martensitic alloys. The slowly cooled specimens contain a mixture of parent 'austenite' and martensite phase. The slightly faster cooled bulk metallic glasses with 2-5 nm sized 'austenite'-like crystalline cluster reveal high strength and large ductility (16%). Shear bands propagate in a slither mode in this spatially inhomogeneous glassy structure and undergo considerable 'thickening' from 5-25 nm. A 'stress induced displacive transformation' is proposed to be responsible for both plasticity and work-hardening-like behavior of these 'M-Glasses'.

For commercial applications of Fe-based bulk amorphous alloys as structural materials, Fe-based bulk amorphous alloys that can be costeffectively and massively produced have been developed using hot metal and ferro-alloys from a steel plant. The alloy Fe68:0C10:5Si4:4B6:5P8:6Al2:0 can be cast into a fully amorphous rod of 3 mm in diameter through a suction casting method. Upon heating the amorphous rod, a sequential crystallization behavior starting with the precipitation of fcc-Fe phase were observed. Since the crystallization kinetics was sluggish, the Fe-based bulk amorphous alloy can be used as a precursor for the fabrication of bulk nanostructured Fe alloy.