Effects of Cd Variations on Microstructures and Mechanical Properties of Al-Cu Alloys

GAO Wenli, WANG Shuai, ZHU Congsong, MAO Guoling, WANG Cui

Abstract

The effects of different Cd contents on the microstructure and mechanical properties of Al-Cu alloy were studied through mechanical properties testing as well as SEM，EDX and TEM. The results show that the alloys with different Cd content have the similar aging response law in artificial aging process at 175 °C. Cd element can promote the precipitation of strengthening phase θ' of Al-Cu alloys. The time for peak aging of 0.19% Cd alloy and 0.36% Cd alloy was shortened and the peak hardness value was obtained upgrade. In the peak aging state, when the Cd element mass-fraction increased from 0.10% to 0.19%, the alloy yield strength increased from 384.2 MPa to 422.8 MPa, and the elongation decreased from 8.5% to 7.1%, but the yield strength did not change and the elongation decreased to 5.86% when the mass-fraction of Cd was 0.36%. TEM shows that the number of precipitated phases in the 0.19% Cd alloy was large and the size was small, so that the precipitation strengthening effect of the alloy was more obvious; the length of precipitated phases in the 0.36wt.% Cd alloy became slightly shorter, and the increase of the number was not obvious. At the same time, there was Cd-rich intercrystalline residual phase on the fracture surface of the alloy containing 0.19wt.% and 0.36wt.% Cd, which was harmful for improving the properties of Al-Cu alloy.

 

 

Keywords: Al-Cu alloys,  Cd element,  θ′ precipitates,  mechanical properties


Full Text:

PDF


References


BYRNE J G, FINE M E, KELLY A. Precipitate hardening in an aluminium–copper alloy[J]. Philosophical Magazine, 1961, 69(6):1119—1145.

LIU S, LUO C, LI G,et al. Effect of pressurizing speed on filling behavior of gradual expansion structure in low pres– sure casting of ZL205A alloy [J]. China Foundry, 2018, 15 (4):276—282.

WU C L, ZHOU B, NIU F J, et al. Deformation–induced phase precipitation strengthening of AlCuMg alloy with high Cu/Mg atomic ratio[J]. Journal of Hunan University(Natural Sciences), 2018, 45(6):1—10. (In Chinese)

GAO B L, CAO Y L, LU Z,et al. The aging behavior of aluminum–lithium alloy 2A66[J]. Journal of Hunan University (Natural Sciences), 2016, 43(6):16—21 (In Chinese)

HARDY H D. The ageing characteristics of ternary Al–Cu alloys with Cd,In,Sn[J]. Journal of the Institute of Metals, 1952,80(9):483—492.

SILCOCD J M, FLOBER H M. Comments on a comparison of early and resent work on the effect of trace additions of Cd,In,or Sn on nucleation and growth of 0´ in Al–Cu alloys [J]. Scripta Materialia, 2002, 46(5):389—394.

HU Y, WANG G, YE M,et al. A precipitation hardening model for Al –Cu –Cd alloys [J]. Materials & Design, 2018,151:123—132.

NOBLE B. Theta –prime precipitation in aluminium –copper–cadmium alloys [J]. Acta Metallurgica, 1968, 16(3):393—401.

WOLVERTON C. Solute–vacancy binding in aluminum[J]. Acta Materialia, 2007, 55 (17):5867—5872.

SHIN D, SHYAM A, LEE S, et al. Solute segregation at the Al/0'–Al2Cu interface in Al–Cu alloys[J]. Acta Materialia, 2017, 141:327—340.

GONG Z,ZHENG Z Q. Effects of Cd element on the deposition process of Al–4Cu alloy [J]. Materials Science and Engineering of Powder Metallurgy, 2018, 23(2):157—163. (In Chinese)

LIU G, ZHANG G J, DING X D, et al. Modeling the strengthening response to aging process of heat–treatable a– luminum alloys containing plate/diss–or rod/needle–shaped precipitates [J]. Materials Science and Engineering:A, 2003, 344(1/2):113—124.


Refbacks

  • There are currently no refbacks.