Thermal expansion behavior of a β-LiAlSiO4/Cu composite

Abstract

A copper matrix composite reinforced by β-LiAlSiO 4 with negative thermal expansion coefficient was fabricated using vacuum hot-pressed sintering technique. The thermal expansion behavior of the composite was investigated, and the average residual stress in the matrix was analyzed by a simple model. The results indicate that the residual stress in the matrix affects the thermal expansion properties. After heat treatment, the coefficient of thermal expansion (CTE) of the composite decreases greatly. The CTE of the composite after thermal cycling between 50-350°C is the lowest.

Phase-Transformation-Induced Extra Thermal Expansion Behavior of (SrxBa1–x)TiO3/Cu Composite

“…The tensile stress acting on the matrix can be relaxed upon heating, and K m is much smaller than K p in the SBT/Cu composite; therefore, it can be concluded that the CTE of the composite decreases during this process on the basis of Equation (1) and our previous studies161725. The SBT phase transformation from the T phase to the C phase leads to a sharp decrease of SBT particle CTE; correspondingly, the quick relaxation of the tensile stress causes the CTE of the Cu matrix to decrease greatly, as shown in Fig.…”

“…In addition, the compressive stress and the tensile stress are simultaneously induced on the SBT particles and on the Cu matrix, respectively, when the composite is cooled from a high temperature because the CTE of the SBT particles is lower than that of the Cu matrix 14 15 . The tensile stress acting on the matrix can be relaxed upon heating, and K m is much smaller than K p in the SBT/Cu composite; therefore, it can be concluded that the CTE of the composite decreases during this process on the basis of Equation (1) and our previous studies 16 17 25 . The SBT phase transformation from the T phase to the C phase leads to a sharp decrease of SBT particle CTE; correspondingly, the quick relaxation of the tensile stress causes the CTE of the Cu matrix to decrease greatly, as shown in Fig.…”

“…In the last decade, many studies have investigated negative-CTE ceramics to reinforce MMCs with a low CTE and high TC, such as β-eucryptite (AlLiSiO 4 )14151617 and ZrW 2 O 8 181920. However, the CTE of β-eucryptite (approximately −0.7 × 10 −6  K −1 ) is not as low as expected and microcracks are easily formed in the bulk β-eucryptite ceramics due to its poor strength.…”

“…Generally, it is convenient method to utilize ceramic reinforcement with a low or negative CTE to reduce the ceramic volume fraction in Ceramic/Cu composite, and then a low CTE and high TC can be simultaneously obtained for the composite. In the last decade, many studies have investigated negative-CTE ceramics to reinforce MMCs with a low CTE and high TC, such as β-eucryptite (AlLiSiO 4 ) 14 15 16 17 and ZrW 2 O 8 18 19 20 . However, the CTE of β-eucryptite (approximately −0.7 × 10 −6 K −1 ) is not as low as expected and microcracks are easily formed in the bulk β-eucryptite ceramics due to its poor strength.…”

A novel Ag based sealant for solid oxide cells with a fully tunable thermal expansion

“…A more promising approach to lower the braze CTE is to introduce a negative thermal expansion (NTE) filler material, which contracts upon heating [32][33][34][35][36][37][38]. A practically important NTE material is LiAlSiO 4 , which has an anisotropic CTE (α a = 8.21 × 10 -6 K -1 and α c = -17.6 × 10 -6 K -1 , 0-1000 °C).…”