Intermetallic compounds at aluminum-to-copper electrical interfaces: effect of temperature and electric current

Previous studies have demonstrated that Al-Cu bimetallic welds have high resistance that can increase further from relatively short term exposure to temperatures above 150°C.

“Previous studies have demonstrated that Al-Cu bimetallic welds have high resistance that can increase further from relatively short term exposure to temperatures above 150 • C [11,12].”

Most studies have not performed heat treatment ageing and the relative resistance increase metric was only identified in a few studies.

“As such, most studies have not performed heat treatment ageing and this metric was only identified in a few studies [11,12].”

Several studies did not specify if bulk conductivity was measured, and in a few studies it was not measured or reported.

“Several studies did not specify if bulk conductivity was measured [11,12,28], and in a few studies it was not measured [30], or reported [13].”

Braunovic & Alexandrov suggest possible explanations for the increased resistance as porosity, cracking, changes in grain sizes, and increased dislocation density across the interface.

“Braunovic & Alexandrov [12] suggest possible explanations for the increased resistance as porosity, cracking, changes in grain sizes, and increased dislocation density across the interface.”

200°C is an important operating condition that has previously limited the utility of welded Al-Cu conductors.

“We chose to show performance at 200 • C as it is an important operating condition that has previously limited the utility of welded Al-Cu conductors [12].”

Braunovic pointed out that temperatures of 200°C and higher often occur in network overload conditions.

“Braunovic [12] has pointed out that temperatures of 200 • C and higher often occur in network overload conditions.”

The activation energy and pre-exponential constant for aluminum and copper interfaces have been reported for several processes.

“The activation energy and pre-exponential constant for aluminum and copper interfaces have been reported for several processes [11][12][13][14][15][16][17][18][19][20][21][42][43][44][45][46].”

A widely used criterion for the integrity of Al-Cu welds is maintaining a total thickness of intermetallic compounds below 2 μm.

“A widely used criterion for the integrity of Al-Cu welds is maintaining a total thickness of intermetallic compounds below 2 μm [11,12,31,40,47,48].”

Fig. 10 shows several studies have reported lower electrical resistance of friction welds since the highly cited Braunovic & Alexandrov characterisation.

“Therefore, it is worth highlighting that Fig. 10 shows several studies have reported lower electrical resistance of friction welds since the highly cited Braunovic & Alexandrov [12] characterisation.”