rows = [
{nom: "nom1", composants: ["composant11", "composant12"]},
{nom: "nom2", composants: ["composant21", "composant22"]}
];
<table>
<ng-container *ngFor="let row of rows">
<tr *ngFor="let composant of row.composants">
<td> {{ composant }} </td>
<td> {{ row.nom }} </td>
</tr>
<ng-container>
</table>