Anomalous thermal expansion in the deep super-cooled liquid region of a ZrCuAlAg bulk metallic glass

Figures & data

Figure 1. DSC and DIL traces of (a) Zr₄₃Cu₄₁Al₈Ag₈ and Zr₄₇Cu₃₇Al₈Ag₈ BMGs.

Figure 2. (a) DIL traces of Zr₄₃Cu₄₁Al₈Ag₈ and Zr₄₇Cu₃₇Al₈Ag₈ BMGs heating to different temperatures and (b) XRD patterns of water-cooled samples.

Figure 3. HRTEM and selected-area electron diffraction of the water-cooled samples.

Table 1. Room temperature densities of the as-cast samples, samples fast cooled from different temperature, and ZrCu, Cu₁₀Zr₇ and AlAg₃ crystals according to the powder diffraction file (PDF) database.

	Zr43Cu41Al8Ag8			ZrCu	Zr47Cu37Al8Ag8				Cu10Zr7	AlAg3
Alloys	As-cast	740 K	758 K	(49-1484)	As-cast	743 K	753 K	763 K	(43-0993)	(28-0034)
Density (gcm^−3)	7.426	7.466	7.547	7.419	7.310	7.358	7.412	7.464	7.707	8.730
Zr: Cu (at%)	51 : 49			50 : 50	56 : 44				41 : 59	–

Notes: The PDF card numbers are indicated in the parentheses. Atomic ratios of Zr to Cu for each composition are also listed. Noting the amorphous matrix are assumed to have the same composition and thus the same ratios of Zr to Cu with those of the as-cast alloys for simplification.

Figure 4. (a1, a2, b1, b2) Colored STEM images and (a3, b3) the change of total characteristic spectral X-ray photon counts along the linear scanning direction of Zr43-740 K and Zr47-743 K samples. (b4) The relative atomic percentage change in the transition region from the nano-crystal Cu₁₀Zr₇ to the amorphous phase in the Zr47-743 K sample.

Figure 5. Thermal expansion traces of Zr47 with different dimensions. The corresponding instrument applied compressive stresses of 0.03–0.3 MPa.

Figure 6. The sketch of the microstructural evolutions behind the anomalous expansion.