Development of Al–Nb–B master alloy with high Nb/B ratio for grain refinement of hypoeutectic Al–Si cast alloys

2019 ◽  
Vol 54 (23) ◽  
pp. 14561-14576 ◽  
Author(s):  
J. Xu ◽  
Y. Li ◽  
B. Hu ◽  
Y. Jiang ◽  
Q. Li
2015 ◽  
Vol 15 (2) ◽  
pp. 51-54 ◽  
Author(s):  
W.K. Krajewski ◽  
J. Buraś ◽  
P.K. Krajewski ◽  
G. Piwowarski

Abstract The paper presents results of measuring attenuation coefficient of the Al-20 wt.% Zn alloy (AlZn20) inoculated with different grain refiners. During experiments the melted alloys were doped with Al-Ti3-C0.15 refining master alloy. Basing on measurements performed by Krautkramer USLT2000 device with 1MHz ultrasound wave frequency it was stated that grain refinement reduces the attenuation coefficient by about 20-25%. However, the examined alloys can be still classified as the high-damping ones of attenuation greater than 150 dB/m.


2013 ◽  
Vol 765 ◽  
pp. 311-315 ◽  
Author(s):  
Leandro Bolzoni ◽  
Magdalena Nowak ◽  
N. Hari Babu

The grain refinement practice using Ti based chemical additions is well established for wrought Al alloys, especially in the last few decades. In the case of Al-Si casting alloys the practice of adding grain refiners and the impact on castability is not well established in industries. The main reason is the chemical instability of conventionally known Ti based grain refiner which reacts with silicon forming intermetallic phases. Recently, researchers at Brunel University have identified a novel chemical composition that can refine the grain structure of Al-Si alloys in an effective way. Over the last year, this novel grain refiner in the form of master alloy was developed and tested in various Al-Si cast alloys that are commonly used in industry. Significant grain refinement is obtained when the master alloy is added to the liquid metal prior to casting. Moreover, the grain size of the Al-Si cast alloys is observed to be less sensitive to cooling rate when the master alloy is added. In this work, the influence of addition of the master alloy on microstructural evolution of various Al-Si alloys cast under various cooling rates is presented.


Author(s):  
Wenxue Fan ◽  
Hai Hao

Abstract Grain refinement has a significant influence on the improvement of mechanical properties of magnesium alloys. In this study, a series of Al–Ti–C-xGd (x = 0, 1, 2, 3) master alloys as grain refiners were prepared by self-propagating high-temperature synthesis. The synthesis mechanism of the Al–Ti–C-xGd master alloy was analyzed. The effects of Al–Ti–C-xGd master alloys on the grain refinement and mechanical properties of AZ31 (Mg-3Al-1Zn-0.4Mn) magnesium alloys were investigated. The results show that the microstructure of the Al–Ti–C-xGd alloy contains α-Al, TiAl3, TiC and the core–shell structure TiAl3/Ti2Al20Gd. The refining effect of the prepared Al–Ti–C–Gd master alloy is obviously better than that of Al–Ti–C master alloy. The grain size of AZ31 magnesium alloy was reduced from 323 μm to 72 μm when adding 1 wt.% Al–Ti–C-2Gd master alloy. In the same condition, the ultimate tensile strength and elongation of as-cast alloy were increased from 130 MPa, 7.9% to 207 MPa, 16.6% respectively.


Author(s):  
Jiawei Yang ◽  
Sarina Bao ◽  
Shahid Akhtar ◽  
Yanjun Li

AbstractIn this work, a systematic study on the interactions between aluminum oxide films and TiB2 grain refiner particles and their effect on grain refinement behavior have been conducted. Oxide films were introduced into a commercial purity aluminum melt by adding AA 6061 alloy chips while the grain refiner particles were introduced by adding Al-3T-1B master alloy. Strong sedimentation of TiB2 grain refiner particles was observed in aluminum melt without chip addition during long-time settling. Most of the TiB2 particles were settled and accumulated at the bottom of crucible. In contrast, the sedimentation of TiB2 particles is much less in the melt with the addition of oxide films. A large fraction of TiB2 particles were found to be adhered to the oxide films located at the top part of the crucible, which inhibited the sedimentation of grain refiner particles. TP-1 type tests were also done to study the grain refinement efficiency of Al-3Ti-1B master alloy under different melt cleanliness and settling time. It is found that sedimentation of TiB2 particles greatly reduces the grain refinement efficiency. The introduction of oxide films seems to slightly alleviate the fading effect. This is owing to the strong adherence between the oxide films and TiB2 particles, which leads to a retardation of particle sedimentation.


2013 ◽  
Vol 749 ◽  
pp. 407-413
Author(s):  
Hong Xu ◽  
Xin Zhang ◽  
Ji Ping Ren ◽  
Min Peng ◽  
Shi Yang ◽  
...  

The mechanical properties and corrosion performances of the ZL101 alloy modified by the composite master alloy were investigated. The results showed that the master alloy had not only obvious effect of grain refinement, but also a significant role in refining dendrite grain of ZL101 alloy. The grain size decreased dramatically from 150μm to 62μm when the addition of composite master alloy is up to 0.5%(mass fraction) and the temperature is 720 for 30 minutes,. Its tensile strength and elongation increased by 27% and 42% respectively. The grain refinement of ZL101 alloy decreased its corrosion performance. The morphology of Si changed into globular from needle modified by NaF, instead of AlTiB.


2016 ◽  
Vol 47 (3) ◽  
pp. 1999-2004 ◽  
Author(s):  
Lei Zhang ◽  
Wei Zhou ◽  
Penghe Hu ◽  
Quan Zhou

2007 ◽  
Vol 29-30 ◽  
pp. 111-115 ◽  
Author(s):  
S.A. Kori ◽  
V. Auradi

In the present work binary Al-3Ti and Al-3B master alloys were prepared at different reaction temperatures in an induction furnace by the reaction of halide salts like potassium fluoborate and potassium titanium fluoride with liquid molten Al. The indigenously developed master alloys were used for grain refinement studies of Al-7Si alloy and evaluated for their grain refining ability by CACCA studies. The present results suggest that, the reaction temperature influences the size, size distribution and morphology of the intermetallic (Al3Ti in Al-3Ti, and AlB2/AlB12 in Al-3B) particles present in Al-3Ti and Al-3B master alloys. Grain refinement studies of Al-7Si alloy reveal that, Al-3Ti and Al-3B master alloys prepared at 8000C-60 min. have shown better grain refining efficiency on Al- 7Si alloy when compared to the master alloys prepared at 9000C-60 min and 10000C-60 min respectively. In addition, B-rich Al-3B master alloy shows efficient grain refinement than Ti rich Al- 3Ti master alloy.


2015 ◽  
Vol 48 (3) ◽  
pp. 890-900 ◽  
Author(s):  
Zhilin Liu ◽  
Dong Qiu ◽  
Feng Wang ◽  
John A. Taylor ◽  
Mingxing Zhang

Adding the peritectic forming element Cu effectively reduced the average grain size of cast Zn by over 85%. At a specified cast condition, the smallest grain size was obtained at 2 wt% Cu addition. A further increase in Cu content led to grain coarsening in the cast Zn–Cu alloys. Although the solute effect of Cu was predominately responsible for the grain refinement through restriction of the grain growth, it was found that the variation of grain size is also closely related to the formation of the pro-peritectic phase, ∊-CuZn4. Crystallographic calculations using the edge-to-edge matching model showed low interatomic misfit and interplanar mismatch between Zn and the ∊-CuZn4phase. In addition, a reproducible h.c.p.–h.c.p. (h.c.p. denotes hexagonal close-packed) orientation relationship between Zn and the ∊-CuZn4particles (located within the Zn grain centres) was also experimentally determined using the electron backscattered diffraction method. This indicated the high potency of the pro-peritectic ∊-CuZn4particles as effective heterogeneous nucleation sites for η-Zn, which further refined the Zn grains. However, when the Cu content was over 2.0 wt%, formation of large ∊-CuZn4particles resulted in grain coarsening of the cast alloys.


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