In situ eutectic Al_(11)La_3/Al composite material with regular arrangement was prepared by zone melt liquid metal cooling directionally solidification under conditions of high temperature gradient G=700K/cm and growt...In situ eutectic Al_(11)La_3/Al composite material with regular arrangement was prepared by zone melt liquid metal cooling directionally solidification under conditions of high temperature gradient G=700K/cm and growth rate R=6.0-20.0μm/s.Superpose diffraction pat- tern of Al_(11)La_3/Al composite shows that the preferred growth direction is[100]Al// [33]Al_(11)La_3,and the habit plane is(002)Al//(116)Al_(11)La_3.A low density(103)twin is ob- served in Al_(11)La_3 and the growth of(103)twin induces to branching to change the interlamellar spacing.展开更多
Bulk metallic glasses (BMGs) with large supercooled liquid region are promising materials for superplastic forming. In this paper, we demonstrate a microstructure-based strategy to pinpoint the composition with the la...Bulk metallic glasses (BMGs) with large supercooled liquid region are promising materials for superplastic forming. In this paper, we demonstrate a microstructure-based strategy to pinpoint the composition with the largest supercooled liquid region in La 86 x Al 14 Cu x (x=16 at%-20 at%) metallic glass system. By monitoring the changes in crystallization behavior of the glassy alloys with composition to search for the alloys exhibiting eutectic crystallization, the glassy alloys with the largest supercooled liquid region in the given alloy system can be found. The metallic glasses with Cu contents of 16 at%-19 at% exhibited two crystallization peaks, and the primary crystallization product was identified to be α-La by means of DSC, XRD and TEM. The increase in Cu content resulted in the decay of the primary crystallization peak and the increase in onset temperature of crystallization, leading to the enlargement of supercooled liquid region. By further suppressing the α-La primary crystallization with increasing Cu content up to 20 at%, the eutectic crystallization of α-La and LaCu 13 through one crystallization reaction occurred upon heating, where the largest supercooled liquid region of 65 K for La 66 Al 14 Cu 20 glassy alloy was located. This study indicats that, in a given glassy alloy system, a larger supercooled liquid region can be achieved by optimizing the alloy compositions to suppress the primary crystallization.展开更多
文摘In situ eutectic Al_(11)La_3/Al composite material with regular arrangement was prepared by zone melt liquid metal cooling directionally solidification under conditions of high temperature gradient G=700K/cm and growth rate R=6.0-20.0μm/s.Superpose diffraction pat- tern of Al_(11)La_3/Al composite shows that the preferred growth direction is[100]Al// [33]Al_(11)La_3,and the habit plane is(002)Al//(116)Al_(11)La_3.A low density(103)twin is ob- served in Al_(11)La_3 and the growth of(103)twin induces to branching to change the interlamellar spacing.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50631010, 50771005 and 50771006)the National Basic Research Program of China (Grant No. 2007CB613900)
文摘Bulk metallic glasses (BMGs) with large supercooled liquid region are promising materials for superplastic forming. In this paper, we demonstrate a microstructure-based strategy to pinpoint the composition with the largest supercooled liquid region in La 86 x Al 14 Cu x (x=16 at%-20 at%) metallic glass system. By monitoring the changes in crystallization behavior of the glassy alloys with composition to search for the alloys exhibiting eutectic crystallization, the glassy alloys with the largest supercooled liquid region in the given alloy system can be found. The metallic glasses with Cu contents of 16 at%-19 at% exhibited two crystallization peaks, and the primary crystallization product was identified to be α-La by means of DSC, XRD and TEM. The increase in Cu content resulted in the decay of the primary crystallization peak and the increase in onset temperature of crystallization, leading to the enlargement of supercooled liquid region. By further suppressing the α-La primary crystallization with increasing Cu content up to 20 at%, the eutectic crystallization of α-La and LaCu 13 through one crystallization reaction occurred upon heating, where the largest supercooled liquid region of 65 K for La 66 Al 14 Cu 20 glassy alloy was located. This study indicats that, in a given glassy alloy system, a larger supercooled liquid region can be achieved by optimizing the alloy compositions to suppress the primary crystallization.
